I have kind of the same problem, but in reverse 
When I run games, they RUN in max of 1440x960 resolution, I’m trying to bump up to 2880x1920.
Good luck! Maybe your solution can help me too?
If anything, here’s my reddit thread:
https://www.reddit.com/r/framework/comments/1g7tfmb/gaming_on_fw13_linux_max_resolution_is_1440x960/