I just did a fresh install of Kubuntu 21.10, installed steam and made sure it was setup to use Proton 6.3-7 and started downloading games forcing them to use Proton as a compatibility layer.
The games install just fine, but give the error "An error occurred while updating *game name* (compatibility tool configuration failed".
I have already gone though the basic Steam troubleshooting steps and the listed advanced tips that applied (as most of them are for Windows/Mac). Nothing has worked. I just switched from Manjaro KDE (VMware Support) and had absolutely no issue getting games from steam to launch via Proton on that Distro.
Any ideas or advise on fixing this?