I cannot reproduce on 9070xt, and it seems like you have a 6600.
This was on Steam version though.
Read through ProtonDB again to check if someone had a similar issue. Not sure exactly why the UI disappears but Num-Lock seems to do the trick (toggles UI on or off), maybe it's because I have Num-Lock on by default.
Nothing extracted yet.
Installed Wildgate from Epic Games through Heroic Games Launcher, using latest version of GE-Proton and default settings for everything. Game loads normally, but when entering the tutorial the UI briefly loads then disappears when one starts moving and won't reappear ever. Couldn't solve through Heroic support so they sent me here. Attaching screenshots and game log. Edit: I added d3dcomp 43 and 47 as indicated by Heroic support, but it didn't change anything. Also checked updates for GPU drivers, none available.
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Log
launch.log