FaceRig (274920): missing UI and camera not detected

Compatibility Report

• Name of the game with compatibility issues: FaceRig
• Steam AppID of the game: 274920

System Information

• GPU: EVGA GeForce GTX 1070Ti SC
• CPU: Core i5 4670K @ 3.8 GHz
• Driver/LLVM version: Nvidia 440.100
• System: Ubuntu 20.04 LTS
• Kernel version: 5.4.0-40-generic
• Link to full system information report as Gist
• Proton version: 4.11-13

I confirm:

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

Log: steam-274920.log

Symptoms

FaceRig opens when using Proton 4.11-13 and selecting the option to bypass the launcher (that doesn't work). It's possible to see the character moving and the background (so, it seems to run fine). However, the UI is missing and the camera is not detected.

With Proton 5.0-9, there's only a black screen.

It doesn't work according to ProtonDB reports, but since there wasn't an issue yet, I created this one. The program is able to open and run, so maybe it's possible to fix.

Reproduction

Open FaceRig with Proton 4.11-13 and bypass the launcher.

Start with the linked steam-274920.log and the reproduction steps, comparing behavior under Proton 4.11-13 and 5.0-9. Review the linked ProtonDB reports for additional observations; the issue is done when FaceRig displays its UI and detects the camera instead of showing a black screen or missing interface.