Participant role dropdown isn't working while trying to add participants

Summary: While trying to add participants (either as a candidate, Manager or HR Specialist) to a performance document, participants can be selected but their roles can't be added (the dropdown just doesn't work). I've created the roles (Peer and Project manager) and they should be showing here ideally.

Content (required): While logged in as Pam.Gardner I'm trying to add participant roles (Peer and Project Manager) to the names of two ids Matt.Wagner and Linda.Swift. I'd created these two roles (Peer and Project Manager) while logged in as Curtis.Feitty, the superadmin ID. However, the dropdown isn't showing the roles against the names. Can you please refer to the image attached and advise where the problem could be?