Retrolink GC USB controller not working

Sometimes when I open the GC controller configuration, it seems to recognize the buttons/controllers, and other times it registers no input.
Either way, the games *do not* respond to the controller at all (so at the moment it is completely unusable on Dolphin).

I can get this controller to work easily with Sixtyforce on N64 games, so it's not the controller itself.

Any wisdom that can be imparted on this issue?