3rd party gaming mouse works before login but stops working afterwards
The first thing I would do is try booting into Safe Mode.

Boot into Safe Mode 

Follow these steps to boot your Mac into Safe Mode: 


Fully shut down your Mac 
Restart your Mac 
Immediately press the Shift key and keep it down 
Let go of the Shift key when you see the login window (NOTE: If you have FileVault enabled you may need to log in twice). 
Take a note of what happens (i.e. does the mouse work properly, etc) 
Exit Safe Mode by restarting your Mac as normal 
Test again when booted normally 


Let me know how these steps went and we'll go from there.