What you’re seeing is normal. When a UAC prompt appears, Windows switches to a protected screen, so Remote Help can’t show it and the technician just sees a black screen.
With Endpoint Privilege Management, this step is skipped. Instead of entering an admin password, approved actions are allowed automatically by policy.
So for the technician, the task just runs with the needed permissions and the screen never goes black. If you still see the issue, it means the task isn’t covered by an EPM rule yet.