Application icons don't show when external monitor connected

[Mark Richards]

If I connect an external display to my Lenovo Thinkpad T420 via display port (laptop screen main display) and click the Applications icon in the dock, I see a brief animation and then tiny little icons appear for a split second before vanishing. The application icons appear as normal if I disconnect my external display. I've attached a screenshot which I managed to take just as the tiny icons were vanishing.

ProblemType: Bug
DistroRelease: Ubuntu 20.04
Package: xorg 1:7.7+19ubuntu14
ProcVersionSignature: Ubuntu 5.4.0-24.28-generic 5.4.30
Uname: Linux 5.4.0-24-generic x86_64
ApportVersion: 2.20.11-0ubuntu27
Architecture: amd64
BootLog: Error: [Errno 13] Permission denied: '/var/log/boot.log'
CasperMD5CheckResult: skip
CompositorRunning: None
CurrentDesktop: ubuntu:GNOME
Date: Thu Apr 16 21:24:32 2020
DistUpgraded: Fresh install
DistroCodename: focal
DistroVariant: ubuntu
ExtraDebuggingInterest: Yes
GraphicsCard:
 Intel Corporation 2nd Generation Core Processor Family Integrated Graphics Controller [8086:0126] (rev 09) (prog-if 00 [VGA controller])
   Subsystem: Lenovo ThinkPad T420 [17aa:21ce]
InstallationDate: Installed on 2020-04-16 (0 days ago)
InstallationMedia: Ubuntu 20.04 LTS "Focal Fossa" - Beta amd64 (20200402)
MachineType: LENOVO 4236PA8
ProcEnviron:
 LANGUAGE=en_GB:en
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=en_GB.UTF-8
 SHELL=/bin/bash
ProcKernelCmdLine: BOOT_IMAGE=/vmlinuz-5.4.0-24-generic root=/dev/mapper/vgubuntu-root ro quiet splash
SourcePackage: xorg
Symptom: display
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 09/05/2016
dmi.bios.vendor: LENOVO
dmi.bios.version: 83ET79WW (1.49 )
dmi.board.asset.tag: Not Available
dmi.board.name: 4236PA8
dmi.board.vendor: LENOVO
dmi.board.version: Not Available
dmi.chassis.asset.tag: No Asset Information
dmi.chassis.type: 10
dmi.chassis.vendor: LENOVO
dmi.chassis.version: Not Available
dmi.modalias: dmi:bvnLENOVO:bvr83ET79WW(1.49):bd09/05/2016:svnLENOVO:pn4236PA8:pvrThinkPadT420:rvnLENOVO:rn4236PA8:rvrNotAvailable:cvnLENOVO:ct10:cvrNotAvailable:
dmi.product.family: ThinkPad T420
dmi.product.name: 4236PA8
dmi.product.version: ThinkPad T420
dmi.sys.vendor: LENOVO
version.compiz: compiz N/A
version.libdrm2: libdrm2 2.4.101-2
version.libgl1-mesa-dri: libgl1-mesa-dri 20.0.4-1ubuntu1
version.libgl1-mesa-glx: libgl1-mesa-glx N/A
version.xserver-xorg-core: xserver-xorg-core 2:1.20.8-2ubuntu2
version.xserver-xorg-input-evdev: xserver-xorg-input-evdev N/A
version.xserver-xorg-video-ati: xserver-xorg-video-ati 1:19.1.0-1
version.xserver-xorg-video-intel: xserver-xorg-video-intel 2:2.99.917+git20200226-1
version.xserver-xorg-video-nouveau: xserver-xorg-video-nouveau 1:1.0.16-1

[Daniel van Vugt (vanvugt)]

Thank you for taking the time to report this bug and helping to make Ubuntu better. This particular bug has already been reported and is a duplicate of bug 1869571, so it is being marked as such. Please look at the other bug report to see if there is any missing information that you can provide, or to see if there is a workaround for the bug. Additionally, any further discussion regarding the bug should occur in the other report. Feel free to continue to report any other bugs you may find.

[Daniel van Vugt (vanvugt)]

Actually it sounds like you will experience both bug 1869571 and bug 1869737, so please subscribe to both.