Fractional scaling results in black screen

[Frank Blah]

Steps to reproduce
==================

1. Open display settings
2. Enable fractional scaling
3. Set particular scale for external and internal monitor

What is expected
================

Working displays

What happened instead
=====================

Experiencing a black screen. I can get the output back by switching to another display output with Super+P, which resets the scaling fraction.

Additional info
===============

Screencast in the attachment.

ProblemType: Bug
DistroRelease: Ubuntu 20.04
Package: xorg 1:7.7+19ubuntu14
ProcVersionSignature: Ubuntu 5.4.0-29.33-generic 5.4.30
Uname: Linux 5.4.0-29-generic x86_64
NonfreeKernelModules: nvidia_modeset nvidia
.proc.driver.nvidia.gpus.0000.01.00.0: Error: [Errno 21] Is a directory: '/proc/driver/nvidia/gpus/0000:01:00.0'
.proc.driver.nvidia.registry: Binary: ""
.proc.driver.nvidia.suspend: suspend hibernate resume
.proc.driver.nvidia.suspend_depth: default modeset uvm
.proc.driver.nvidia.version:
 NVRM version: NVIDIA UNIX x86_64 Kernel Module 440.64 Fri Feb 21 01:17:26 UTC 2020
 GCC version:
ApportVersion: 2.20.11-0ubuntu27
Architecture: amd64
BootLog: Error: [Errno 13] Permission denied: '/var/log/boot.log'
CasperMD5CheckResult: skip
CompizPlugins: No value set for `/apps/compiz-1/general/screen0/options/active_plugins'
CompositorRunning: None
CurrentDesktop: ubuntu:GNOME
Date: Fri May 15 11:19:57 2020
DistUpgraded: Fresh install
DistroCodename: focal
DistroVariant: ubuntu
ExtraDebuggingInterest: Yes
GraphicsCard:
 NVIDIA Corporation TU117GLM [Quadro T2000 Mobile / Max-Q] [10de:1fb8] (rev a1) (prog-if 00 [VGA controller])
   Subsystem: Hewlett-Packard Company TU117GLM [Quadro T2000 Mobile / Max-Q] [103c:8611]
InstallationDate: Installed on 2020-05-11 (3 days ago)
InstallationMedia: Ubuntu 20.04 LTS "Focal Fossa" - Release amd64 (20200423)
MachineType: HP HP ZBook 15 G6
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-5.4.0-29-generic root=UUID=9895584a-6648-494d-9d91-e64ba192dd95 ro quiet splash vt.handoff=7
SourcePackage: xorg
Symptom: display
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 09/25/2019
dmi.bios.vendor: HP
dmi.bios.version: R92 Ver. 01.02.01
dmi.board.name: 860F
dmi.board.vendor: HP
dmi.board.version: KBC Version 65.23.00
dmi.chassis.type: 10
dmi.chassis.vendor: HP
dmi.modalias: dmi:bvnHP:bvrR92Ver.01.02.01:bd09/25/2019:svnHP:pnHPZBook15G6:pvr:rvnHP:rn860F:rvrKBCVersion65.23.00:cvnHP:ct10:cvr:
dmi.product.family: 103C_5336AN HP ZBook 15
dmi.product.name: HP ZBook 15 G6
dmi.product.sku: 6CJ09AV
dmi.sys.vendor: HP
version.compiz: compiz N/A
version.libdrm2: libdrm2 2.4.101-2
version.libgl1-mesa-dri: libgl1-mesa-dri 20.0.4-2ubuntu1
version.libgl1-mesa-glx: libgl1-mesa-glx 20.0.4-2ubuntu1
version.nvidia-graphics-drivers: nvidia-graphics-drivers-* 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 1873403, 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.