Can't work out how to stop keyboard and controller switching

My controller is switching between keyboard/mouse inputs and controller inputs. I am unable to navigate any type of menu due to this.
Video below showing the issue: (it may be hard to see but for the first 5 seconds-ish you can see my mouse flickering in and out - this is what happens whenever I use my controller. I have looked up multiple times and have not gotten a conclusive answer)

https://reddit.com/link/1l262hp/video/onhef2l23o4f1/player

PLEASE DO NOT SUGGEST:
Settings > Desktop Layout > Enable/Disable Steam Input NEITHER MODES WORKS
Any type of resolution using Big Picture Mode NO METHODS HAVE WORKED