Game doesn't recognize extra mouse buttons?

I bought a new mouse (Sharkoon SGM 1). I installed the current driver and software for the mouse. However, games (e.g. Fortnite) do not recognize 3 of the 5 extra mouse buttons on the side when I assign a function to this button. Does anyone have a solution?

Uninstall the drivers (the software) and set the button assignments to the mouse buttons in the game settings.

I could well imagine that it will work then.

Thanks, I'll try immediately

Here you go, good luck!