Roles and permissions

I'm testing a new plugin, but when I log in as a Teacher to try to use it, it tells me that I don't have permission to managegroups. 

I've been trying for hours to hunt down the cause of this. The Teacher role has it set to Allow and I don't see any changes to this in any of the course categories.  HOWEVER,...

...when I "Check permissions in System" I see that it's set to NO! And it's the same for ANY user in a teacher role that I check. Any ideas how I can track down the reason behind this? It's driving me ka-razy!