We created a Rule to insist on group members being accounts (and not groups nor people).

When UI is used to try to add an invalid member (due to a subject-source-restricting rule), the error message says "Entity must be a group." This should be wrong type of entity: Mus be account.

 

Also, the Rule would not render properly in the UI rule list for the group

 

Finally, the Rule could not be edited; it displayed an xml error message, I think.