We just set up a GPO which logs out inactive/disconnected RDP sessions after a 1 hour timeout, as so...
which works great, exactly as expected.
We then have a group to which we can add users, in case they need to run a long-running process, that will exclude them for as long as they are in the group, configured as so.
However this does not seem to be working. It still terminates the session after the inactivity period. Based on this link, I think I'm doing this correctly.
And when logging in my test session, I ran
gpresult, and verified that I AM in the exclusion group.