Compatibility Report

• Name of the game with compatibility issues: Left 4 Dead 2 Authoring Tools
• Steam AppID of the game: 563

System Information

• GPU: RTX 2080 Ti
• Driver/LLVM version: 440.100
• Kernel version: 5.7.9-1 (Manjaro)
• Full system information report: Gist
• Proton version: 5.0-9

I confirm:

• [x] that I haven't found an existing compatibility report for this game.
• [x] that I have checked whether there are updates for my system available.

steam-563.log

Symptoms

The user interfaces across the board aren't scaled properly, so everything is tiny.
Opening the Hammer Editor and starting a new project causes the window to flicker then becomes almost solid black and the majority of UI elements disappear.

Reproduction

Reproduction Example Video Clip.zip