Originally posted by kruzilla:

[quote=
I'm using an 8bitdo Pro 2 controller. Works on every system.

I looked up the controller, it looks nice, good find! It claims to be compatible with Steam on both Mac and Windows operating systems, which is good. If it works on every other system you've tried it on, maybe try disconnecting the controller from Steam and somehow having Steam forget it, then try to reconnect? Otherwise, maybe a new controller would work.