Moving a source to a group with a defined regex fails without a UI error

If a group is created with a regex, metadata sources that don't match cannot be assigned to that group. If the admin attempts to assign the source to the group with the regex, nothing will happen in the UI. In dev tools, the error that comes from the backend is:

{ "errorCode": "400", "errorMessage": "EntityId is not a pattern match to the group" }