Genplus gx retroarch mode button problem

I am using genplus gx on retroarch and the 6 button / 2 button mode button (select on my controller) does not work in retropie. I am using wii classic controllers and in the retroarch menu input settings i select my select button as mode button (also preset in cfg file) and it does nothing. Ive tried setting to a different button still same thing. One street fighter game sees it as a 3 button controller another sees it as a 6 button controller. Any help would be appreciated.