ToME: the Tales of Maj'Eyal

While transitioning from Reknor 3 to 4, my game got stuck in what appeared to be an endless loop while generating the next level. The progress bar bounced back and forth longer and faster than usual, but never stopped. After waiting for a while I closed the game (using End Process in task manager). Now when I reload my save, I see only a black background (usual UI, but no terrain, no character, etc). I can't progress turns (resting never stops unless I press ESC, and pressing 5 on the keypad doesn't actually progress time, meaning my rod of recall can never finish).

A while before this, I changed the way the game saved areas (set zone save per level option to enabled).

Looking in my save game directory, I see no Reknor 4 level file, despite my character showing as existing on Reknor 4 in game.