I ran into this exact same problem and spent a painfully long week trying to fix it. Unfortunately I couldn't... My only solution was to switch distros and the problem disappeared. I went with Fedora and now every game works like a dream. I still don't know what the issue was but it seems to be something to do with having an AMD system and using steam on Ubuntu.
Probably not the solution you're looking for, but it is a solution!
I ran into this exact same problem and spent a painfully long week trying to fix it. Unfortunately I couldn't... My only solution was to switch distros and the problem disappeared. I went with Fedora and now every game works like a dream. I still don't know what the issue was but it seems to be something to do with having an AMD system and using steam on Ubuntu.
Probably not the solution you're looking for, but it is a solution!