I cant use my mouse's side buttons for Badlion Client

For some reason my Launcher for Minecraft doesnt work so I just use Badlion Client. Honestly I never really had any problems with it until i wanted to change my controls in mc. I wanted my side buttons on the mouse to go to Hotbar 1 and 5. Badlion registered those buttons as key.keyboard and when I tried to use those side buttons they didn't work. I tried to look in the controls if there is anything wrong but honestly i have no idea. plz help.

This is a known issue and it's actually a minecraft problem not just badlion, what most of us do is change our side buttons to a key, something you already use as the hotkey for that slot or if you use it for shift and similar then change it to shift..

Is your mouse a mouse with software? Maybe u have to set the side buttons to 1 and 5...