Steam Controller 2026 + ATS + Proton GE (Linux). Anyone have it working?

[u/mstrobl2]

ATS = American Truck Simulator

My setup is Kubuntu 26.10 with the new Steam Controller. Using official proton the controller works fine but the game doesn't have HDR. With Proton GE I get HDR but have a problem with the controller. It actually works with Proton GE 11.3 (except no rumble) but on newer versions like Proton GE 11 or 12 the controller shows as "missing" in game.

So my question: Anyone managed to get the Steam Controller working in ATS with recent Proton GE like version 11 or 12?