"Reach for the Sky" basement Ddoor may have been disabled. I just ran that and my door instantly vanished after taking the orb -- MUCH earlier than is usual. It really wasn't all that big a deal, but it sure was a big surprise. I'll be running it again (and again .. and .. ) and so will find out for certain if it's that or just an anomaly for that particular one run.
I'd suggest if running it at high reaper with a group to wait for the orb grabber before all heading up just in case.
"Oath of Vengeance" door out of early levers isn't the only speed up. The best one is skipping the entire graveyard if you run in, flip the last lever, grab the skull / launch the beam, then door out. The undead all spawn too slowly to agro on the run in, so you'll leave a full unagro GY behind.
Be SURE you let your party know beam is coming early, especially on HC. That way you won't feel guilty when someone dies from it.