System information:
It's not only on DOOM but in a lot of games. From what I've been testing I can list this ones with the same problem:
Hello @nimbius, issues with games run with Proton are being tracked in Proton's issue tracker. The closest issue report to this issue is https://github.com/ValveSoftware/Proton/issues/204.
Your system information
Issue is being reported here as well for beta client
https://steamcommunity.com/app/221410/discussions/8/1734336452582696216/
mouse cursor movement does not work in DOOM for steamplay beta test. mouse moves initially, then on first click mouse freezes. mouse will only move if scroll button is held, or while l/r button are pressed.
Steps for reproducing this issue: