Re: Mouse key binding broken - button 6 issue

A user said in that post: 

https://www.reddit.com/r/battlefield2042/comments/q2gslb/i_cant_rebind_my_mouse_keys_does_anyone_know_how/?utm_source=share&utm_medium=web2x&context=3

(by Davisem94)

that you can solve it by clearing the cache folder in My Documents-->Battlefield2042.
I had the same problem as you and it worked for me.
Good luck.