I created a test OVAL file to dig into this a little bit more.

$ cat com.ubuntu.test.cve.oval.xml 
<oval_definitions
    xmlns="http://oval.mitre.org/XMLSchema/oval-definitions-5"
    xmlns:ind-def="http://oval.mitre.org/XMLSchema/oval-definitions-5#independent"
    xmlns:oval="http://oval.mitre.org/XMLSchema/oval-common-5"
    xmlns:unix-def="http://oval.mitre.org/XMLSchema/oval-definitions-5#unix"
    xmlns:linux-def="http://oval.mitre.org/XMLSchema/oval-definitions-5#linux"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://oval.mitre.org/XMLSchema/oval-common-5 oval-common-schema.xsd   http://oval.mitre.org/XMLSchema/oval-definitions-5 oval-definitions-schema.xsd   http://oval.mitre.org/XMLSchema/oval-definitions-5#independent independent-definitions-schema.xsd   http://oval.mitre.org/XMLSchema/oval-definitions-5#unix unix-definitions-schema.xsd   http://oval.mitre.org/XMLSchema/oval-definitions-5#macos linux-definitions-schema.xsd">

    <generator>
        <oval:product_name>Canonical CVE OVAL Generator</oval:product_name>
        <oval:product_version>1.1</oval:product_version>
        <oval:schema_version>5.11.1</oval:schema_version>
        <oval:timestamp>2020-03-03T10:37:20</oval:timestamp>
    </generator>

    <definitions>
        <definition class="vulnerability" id="oval:com.ubuntu.test:def:200" version="1">
            <metadata>
                <title>CVE-1970-0200 on Ubuntu - high.</title>
                <description>OVAL TEST
				To simulate a vunlerable package with no available patch being installed on the system.
				Checks for the 'linux-doesnotexist-base' package to be installed on the system.
				There is no 'linux-doesnotexist-base' package so it will never be installed.
				This test should always return false (not vulnerable) and appear green in the report.</description>
                <affected family="unix">
                    <platform>Ubuntu</platform>
                </affected>
                <advisory>
                    <severity>High</severity>
                    <rights>Copyright (C) 2018 Canonical Ltd.</rights>
                    <public_date>2018-01-24 10:29:00 UTC</public_date>
                </advisory>
            </metadata>
            <criteria>
                <criterion test_ref="oval:com.ubuntu.test:tst:200" comment="linux-doesnotexist-base package is affected and needs fixing." />
            </criteria>
        </definition>
        <definition class="vulnerability" id="oval:com.ubuntu.test:def:300" version="1">
            <metadata>
                <title>CVE-1970-0300 on Ubuntu - high.</title>
                <description>OVAL TEST
				This is the opposite of the previous test, just to confirm that oscap correct detects the installed package
				Checks for the 'linux-base' package to be installed on the system.
				There should always be a 'linux-base' package installed.
				This test should always return true (vulnerable) and appear red/orange in the report.</description>
                <affected family="unix">
                    <platform>Ubuntu</platform>
                </affected>
                <advisory>
                    <severity>High</severity>
                    <rights>Copyright (C) 2018 Canonical Ltd.</rights>
                    <public_date>2018-01-24 10:29:00 UTC</public_date>
                </advisory>
            </metadata>
            <criteria>
                <criterion test_ref="oval:com.ubuntu.test:tst:300" comment="linux-base package in xenial is affected and needs fixing." />
            </criteria>
        </definition>
        <definition class="vulnerability" id="oval:com.ubuntu.test:def:400" version="1">
            <metadata>
                <title>CVE-1907-0400 on Ubuntu - high.</title>
                <description>OVAL TEST
				To simulate an installed package that is vulnerable when there is an available version to fix the CVE.
				Checks for version less than '99:99.9.9+dfsg-9ubuntu9.9' of the 'linux-base' package to be installed on the system.
				There should always be a 'linux-base' package installed and the version will be less than '99:99.9.9+dfsg-9ubuntu9.9'.
				This test should always return true (vulnerable) and appear red/orange in the report.</description>
                <affected family="unix">
                    <platform>Ubuntu</platform>
                </affected>
                <advisory>
                    <severity>High</severity>
                    <rights>Copyright (C) 2017 Canonical Ltd.</rights>
                    <public_date>2017-03-27 17:59:00 UTC</public_date>
                    <public_date_at_usn>2017-03-27</public_date_at_usn>
                </advisory>
            </metadata>
            <criteria>
                <criterion test_ref="oval:com.ubuntu.test:tst:400" comment="linux-base package in xenial was vulnerable but has been fixed (note: '99:99.9.9p9+dfsg-9ubuntu9.9')." />
            </criteria>
        </definition>
        <definition class="vulnerability" id="oval:com.ubuntu.test:def:500" version="1">
            <metadata>
                <title>CVE-1907-0500 on Ubuntu - high.</title>
                <description>OVAL TEST
				To simulate an installed package that is updated to a patched version and not vulnerable to CVE.
				Checks for version less than '00:00.0.0+dfsg-0ubuntu0.0' of the 'linux-base' package to be installed on the system.
				There should always be a 'linux-base' package installed and the version will be greater than '00:00.0.0+dfsg-0ubuntu0.0'.
				This test should always return false (not vulnerable) and appear green in the report.</description>
                <affected family="unix">
                    <platform>Ubuntu</platform>
                </affected>
                <reference source="CVE" ref_id="CVE-2017-6458" ref_url="https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2017-6458" />
                <advisory>
                    <severity>High</severity>
                    <rights>Copyright (C) 2017 Canonical Ltd.</rights>
                    <public_date>2017-03-27 17:59:00 UTC</public_date>
                    <public_date_at_usn>2017-03-27</public_date_at_usn>
                </advisory>
            </metadata>
            <criteria>
                <criterion test_ref="oval:com.ubuntu.test:tst:500" comment="linux-base package in xenial was vulnerable but has been fixed (note: '0:00.0.0p0+dfsg-0ubuntu0.0')." />
            </criteria>
        </definition>
    </definitions>
    <tests>
        <linux-def:dpkginfo_test id="oval:com.ubuntu.test:tst:200" version="1" check_existence="at_least_one_exists" check="at least one" comment="Does the 'linux-doesnotexist-base' package exist?">
            <linux-def:object object_ref="oval:com.ubuntu.test:obj:200"/>
        </linux-def:dpkginfo_test>
        <linux-def:dpkginfo_test id="oval:com.ubuntu.test:tst:300" version="1" check_existence="at_least_one_exists" check="at least one" comment="Does the 'linux-base' package exist?">
            <linux-def:object object_ref="oval:com.ubuntu.test:obj:300"/>
        </linux-def:dpkginfo_test>
        <linux-def:dpkginfo_test id="oval:com.ubuntu.test:tst:400" version="1" check_existence="at_least_one_exists" check="at least one" comment="Does the 'linux-base' package exist and is the version less than '99:99.9.9p9+dfsg-9ubuntu9.9'?">
            <linux-def:object object_ref="oval:com.ubuntu.test:obj:400"/>
        <linux-def:state state_ref="oval:com.ubuntu.test:ste:400" />
        </linux-def:dpkginfo_test>
        <linux-def:dpkginfo_test id="oval:com.ubuntu.test:tst:500" version="1" check_existence="at_least_one_exists" check="at least one" comment="Does the 'linux-base' package exist and is the version less than '0:00.0.0p0+dfsg-0ubuntu0.0'?">
            <linux-def:object object_ref="oval:com.ubuntu.test:obj:500"/>
        <linux-def:state state_ref="oval:com.ubuntu.test:ste:500" />
        </linux-def:dpkginfo_test>
    </tests>
    <objects>
        <linux-def:dpkginfo_object id="oval:com.ubuntu.test:obj:200" version="1" comment="The 'linux-doesnotexist-base' package binaries.">
            <linux-def:name var_ref="oval:com.ubuntu.test:var:200" var_check="at least one" />
        </linux-def:dpkginfo_object>
        <linux-def:dpkginfo_object id="oval:com.ubuntu.test:obj:300" version="1" comment="The 'linux-base' package binaries.">
            <linux-def:name var_ref="oval:com.ubuntu.test:var:300" var_check="at least one" />
        </linux-def:dpkginfo_object>
        <linux-def:dpkginfo_object id="oval:com.ubuntu.test:obj:400" version="1" comment="The 'linux-base' package binaries.">
            <linux-def:name var_ref="oval:com.ubuntu.test:var:400" var_check="at least one" />
        </linux-def:dpkginfo_object>
        <linux-def:dpkginfo_object id="oval:com.ubuntu.test:obj:500" version="1" comment="The 'linux-base' package binaries.">
            <linux-def:name var_ref="oval:com.ubuntu.test:var:500" var_check="at least one" />
        </linux-def:dpkginfo_object>
    </objects>
    <states>
        <linux-def:dpkginfo_state id="oval:com.ubuntu.test:ste:400" version="1" comment="The package version is less than '99:99.9.9p9+dfsg-9ubuntu9.9'.">
            <linux-def:evr datatype="debian_evr_string" operation="less than">99:99.9.9p9+dfsg-9ubuntu9.9</linux-def:evr> 
        </linux-def:dpkginfo_state>
        <linux-def:dpkginfo_state id="oval:com.ubuntu.test:ste:500" version="1" comment="The package version is less than '0:00.0.0p0+dfsg-0ubuntu0.0'.">
            <linux-def:evr datatype="debian_evr_string" operation="less than">0:00.0.0p0+dfsg-0ubuntu0.0</linux-def:evr>
        </linux-def:dpkginfo_state>
    </states>
    <variables>
        <constant_variable id="oval:com.ubuntu.test:var:200" version="1" datatype="string" comment="'linux-doesnotexist-base' package binaries">
            <value>linux-doesnotexist-base</value>
        </constant_variable>
        <constant_variable id="oval:com.ubuntu.test:var:300" version="1" datatype="string" comment="'linux-base' package binaries">
            <value>linux-base</value>
        </constant_variable>
        <constant_variable id="oval:com.ubuntu.test:var:400" version="1" datatype="string" comment="'linux-base' package binaries">
            <value>linux-base</value>
        </constant_variable>
        <constant_variable id="oval:com.ubuntu.test:var:500" version="1" datatype="string" comment="'linux-base' package binaries">
            <value>linux-base</value>
        </constant_variable>
    </variables>
</oval_definitions>

I can run oscap against that test oval file successfully on trusty, xenial and bionic VMs with the same results:

markmorlino@sec-bionic-amd64:~$ oscap oval eval --report report.html com.ubuntu.test.cve.oval.xml
Definition oval:com.ubuntu.test:def:500: false
Definition oval:com.ubuntu.test:def:400: true
Definition oval:com.ubuntu.test:def:300: true
Definition oval:com.ubuntu.test:def:200: false
Evaluation done.

I see very similar looking errors when I attempt to run the same oscap command on eoan and focal:

markmorlino@sec-eoan-amd64:~$ oscap oval eval --report report.html com.ubuntu.test.cve.oval.xml
W: oscap:     Can't receive message: 103, Software caused connection abort.
Definition oval:com.ubuntu.test:def:500: error
W: oscap:     Can't receive message: 103, Software caused connection abort.
Definition oval:com.ubuntu.test:def:400: error
W: oscap:     Can't receive message: 103, Software caused connection abort.
Definition oval:com.ubuntu.test:def:300: error
Definition oval:com.ubuntu.test:def:200: false
OpenSCAP Error: Probe with PID=21031 has been killed with signal 11 [../../../../../src/OVAL/probes/SEAP/sch_pipe.c:178]
Probe with PID=21031 has core dumped. [../../../../../src/OVAL/probes/SEAP/sch_pipe.c:182]
Item corresponding to object 'oval:com.ubuntu.test:obj:500' from test 'oval:com.ubuntu.test:tst:500' has an unknown flag. This may indicate a bug in OpenSCAP. [../../../../src/OVAL/results/oval_resultTest.c:914]
Probe with PID=21047 has been killed with signal 11 [../../../../../src/OVAL/probes/SEAP/sch_pipe.c:178]
Probe with PID=21047 has core dumped. [../../../../../src/OVAL/probes/SEAP/sch_pipe.c:182]
Item corresponding to object 'oval:com.ubuntu.test:obj:400' from test 'oval:com.ubuntu.test:tst:400' has an unknown flag. This may indicate a bug in OpenSCAP. [../../../../src/OVAL/results/oval_resultTest.c:914]
Probe with PID=21062 has been killed with signal 11 [../../../../../src/OVAL/probes/SEAP/sch_pipe.c:178]
Probe with PID=21062 has core dumped. [../../../../../src/OVAL/probes/SEAP/sch_pipe.c:182]
Item corresponding to object 'oval:com.ubuntu.test:obj:300' from test 'oval:com.ubuntu.test:tst:300' has an unknown flag. This may indicate a bug in OpenSCAP. [../../../../src/OVAL/results/oval_resultTest.c:914]


I also see these in /var/log/syslog:
Mar  4 09:13:50 sec-eoan-amd64 kernel: [12899.335657] traps: probe_worker[21104] general protection fault ip:7f44012cdc31 sp:7f43f9443138 error:0 in libc-2.30.so[7f44011f4000+178000]
Mar  4 09:13:51 sec-eoan-amd64 kernel: [12899.427120] traps: probe_worker[21114] general protection fault ip:7fb6b97f0c31 sp:7fb6b1966138 error:0 in libc-2.30.so[7fb6b9717000+178000]
Mar  4 09:13:51 sec-eoan-amd64 kernel: [12899.519719] traps: probe_worker[21124] general protection fault ip:7effa7110c31 sp:7eff9f286138 error:0 in libc-2.30.so[7effa7037000+178000]




My test