Ubuntu 19.10 incorrectly selects audio output source

[Bickhaus]

I have two monitors hooked up to an AMD RX570 via displayport. In the sound settings they appear as "Ellesmere HDMI Audio [Radeon RX 470/480/560/570/580/590]" and Ubuntu 19.10 selected one of them as the output device by default. My speakers are connected to a green mini-jack line out jack on the motherboard. Switching to line out gives me sound, and I have no other issues.

Originally, I had upgraded to the beta from the command line in 19.04. I had not experienced this issue in 19.04, but upon first booting into 19.10, I had to switch output device back to line out. A fresh install of the beta iso gave the same result (one of my monitors connected to my video card was selected by default). Note that my monitors are Dell U2415s but they do have line out jacks.

ProblemType: Bug
DistroRelease: Ubuntu 19.10
Package: alsa-base 1.0.25+dfsg-0ubuntu5
ProcVersionSignature: Ubuntu 5.3.0-13.14-generic 5.3.0
Uname: Linux 5.3.0-13-generic x86_64
ApportVersion: 2.20.11-0ubuntu7
Architecture: amd64
AudioDevicesInUse:
 USER PID ACCESS COMMAND
 /dev/snd/controlC1: bick 1719 F.... pulseaudio
 /dev/snd/controlC0: bick 1719 F.... pulseaudio
CurrentDesktop: ubuntu:GNOME
Date: Wed Oct 2 00:19:28 2019
InstallationDate: Installed on 2019-10-02 (0 days ago)
InstallationMedia: Ubuntu 19.10 "Eoan Ermine" - Beta amd64 (20190926.1)
PackageArchitecture: all
ProcEnviron:
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=en_US.UTF-8
 SHELL=/bin/bash
SourcePackage: alsa-driver
Symptom: audio
Symptom_AlsaPlaybackTest: ALSA playback test through plughw:HDMI failed
Symptom_Card: Ellesmere HDMI Audio [Radeon RX 470/480 / 570/580/590] - HDA ATI HDMI
Symptom_DevicesInUse:
 USER PID ACCESS COMMAND
 /dev/snd/controlC1: bick 1719 F.... pulseaudio
 /dev/snd/controlC0: bick 1719 F.... pulseaudio
Symptom_Jack: Digital Out, HDMI
Symptom_Type: No sound at all
Title: [System Product Name, ATI R6xx HDMI, Digital Out, HDMI] No sound at all
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 09/12/2019
dmi.bios.vendor: American Megatrends Inc.
dmi.bios.version: 1820
dmi.board.asset.tag: Default string
dmi.board.name: PRIME B450-PLUS
dmi.board.vendor: ASUSTeK COMPUTER INC.
dmi.board.version: Rev X.0x
dmi.chassis.asset.tag: Default string
dmi.chassis.type: 3
dmi.chassis.vendor: Default string
dmi.chassis.version: Default string
dmi.modalias: dmi:bvnAmericanMegatrendsInc.:bvr1820:bd09/12/2019:svnSystemmanufacturer:pnSystemProductName:pvrSystemVersion:rvnASUSTeKCOMPUTERINC.:rnPRIMEB450-PLUS:rvrRevX.0x:cvnDefaultstring:ct3:cvrDefaultstring:
dmi.product.family: To be filled by O.E.M.
dmi.product.name: System Product Name
dmi.product.sku: SKU
dmi.product.version: System Version
dmi.sys.vendor: System manufacturer

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.