We noticed that in sumac.3 that the Gradebook filter for Student Groups > Cohorts is disabled even though we granted Staff or Admin roles to the course user. See picture for details about the cohort drop-down being grayed out.
So it seems the answer to your question (Do you have to be a Discussion Admin or have other discussion roles to have this Cohort Filter not disabled?) is Yes?
If you think that’s a bug, I’d file an issue on the repo!
I think I would classify this as a bug, with the fix being that the cohorts endpoint should check if someone is staff or admin (not discussions staff or admin). I don’t think the IsStaffOrAdmin class itself should change because not sure what downstream effects it would have. Does that make sense?