Bugged 3D display of multimaterial meshes after last Radeon driver update

[Pablo Roldán]

After the last driver update for my Radeon HD 7750 Im having viewport problems in Blender when displaying meshes with multiple materials (see attached screenshot).

This happens both with both the latest version of Blender snap and the direct download from Blender.org
I also have an older version installed and is having the same problem.

It all worked fine before the driver update.

Just in case these are the last lines from running grep "upgrade " /var/log/dpkg.log
:

2020-06-20 00:48:38 upgrade xserver-xorg-legacy-hwe-18.04:amd64 2:1.20.5+git20191008-0ubuntu1~18.04.1 2:1.20.8-2ubuntu2.1~18.04.1
2020-06-20 00:48:39 upgrade xserver-xorg-core-hwe-18.04:amd64 2:1.20.5+git20191008-0ubuntu1~18.04.1 2:1.20.8-2ubuntu2.1~18.04.1
2020-06-20 00:48:40 upgrade xserver-xorg-video-amdgpu-hwe-18.04:amd64 19.0.1-1ubuntu1~18.04.1 19.1.0-1~18.04.1
2020-06-20 00:48:40 upgrade xserver-xorg-video-radeon-hwe-18.04:amd64 1:19.0.1-1ubuntu1~18.04.1 1:19.1.0-1~18.04.1
2020-06-20 00:48:41 upgrade xserver-xorg-video-ati-hwe-18.04:amd64 1:19.0.1-1ubuntu1~18.04.1 1:19.1.0-1~18.04.1

ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: xorg 1:7.7+19ubuntu7.1
ProcVersionSignature: Ubuntu 5.3.0-59.53~18.04.1-generic 5.3.18
Uname: Linux 5.3.0-59-generic x86_64
ApportVersion: 2.20.9-0ubuntu7.15
Architecture: amd64
CompizPlugins: No value set for `/apps/compiz-1/general/screen0/options/active_plugins'
CompositorRunning: None
CurrentDesktop: Budgie:GNOME
Date: Mon Jun 22 16:31:31 2020
DistUpgraded: Fresh install
DistroCodename: bionic
DistroVariant: ubuntu
DkmsStatus:
 openrazer-driver, 2.8.0, 5.3.0-53-generic, x86_64: installed
 openrazer-driver, 2.8.0, 5.3.0-59-generic, x86_64: installed
ExtraDebuggingInterest: Yes, if not too technical
GraphicsCard:
 Advanced Micro Devices, Inc. [AMD/ATI] Cape Verde PRO [Radeon HD 7750/8740 / R7 250E] [1002:683f] (prog-if 00 [VGA controller])
   Subsystem: ASUSTeK Computer Inc. Cape Verde PRO [Radeon HD 7750/8740 / R7 250E] [1043:0427]
InstallationDate: Installed on 2019-08-03 (324 days ago)
InstallationMedia: Ubuntu-Budgie 18.04.2 LTS "Bionic Beaver" - Release amd64 (20190210)
MachineType: System manufacturer System Product Name
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-5.3.0-59-generic root=UUID=bf94f108-3b15-444b-a40a-414115dcfedd ro quiet splash vt.handoff=1
SourcePackage: xorg
Symptom: display
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 02/25/2014
dmi.bios.vendor: American Megatrends Inc.
dmi.bios.version: 1107
dmi.board.asset.tag: To be filled by O.E.M.
dmi.board.name: P8H61-M LX3 R2.0
dmi.board.vendor: ASUSTeK COMPUTER INC.
dmi.board.version: Rev X.0x
dmi.chassis.asset.tag: Asset-1234567890
dmi.chassis.type: 3
dmi.chassis.vendor: Chassis Manufacture
dmi.chassis.version: Chassis Version
dmi.modalias: dmi:bvnAmericanMegatrendsInc.:bvr1107:bd02/25/2014:svnSystemmanufacturer:pnSystemProductName:pvrSystemVersion:rvnASUSTeKCOMPUTERINC.:rnP8H61-MLX3R2.0:rvrRevX.0x:cvnChassisManufacture:ct3:cvrChassisVersion:
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
version.compiz: compiz N/A
version.libdrm2: libdrm2 2.4.101-2~18.04.1
version.libgl1-mesa-dri: libgl1-mesa-dri 19.2.8-0ubuntu0~18.04.3
version.libgl1-mesa-glx: libgl1-mesa-glx 19.2.8-0ubuntu0~18.04.3
version.xserver-xorg-core: xserver-xorg-core N/A
version.xserver-xorg-input-evdev: xserver-xorg-input-evdev N/A
version.xserver-xorg-video-ati: xserver-xorg-video-ati N/A
version.xserver-xorg-video-intel: xserver-xorg-video-intel N/A
version.xserver-xorg-video-nouveau: xserver-xorg-video-nouveau N/A