ToME: the Tales of Maj'Eyal

First let me express my appreciation for creating this great game! I've played dozens of games of Tome 2 and quite a pile of Tome 4 (never come close to winning tho', but I keep trying), so thank you for all your hard work.

Anyway upon entering the second level of the lost merchant quest there was no Assassin Lord to be found. Killed off all his cronies, merchant got killed after an alarm trap summoned a small army, but no Assassin Lord, no stairs, and Rod of Recall doesn't work down here. The quest still shows as active. Is there any way I can cheat my way back to the world map?

What might be the case here:

I've noticed, the new AI tends to make heavily wounded characters flee.
The Assasin Lord is pretty good at being invisible, so it is possible that he is hiding somewhere, regaining his hitpoints.
Try resting, and see if you are attacked after a while.

He doesn't seem to be on the map at all, I've stepped on every space (even dug out all the walls). There's nothing but myself and 4 open doors.

He wasn't standing below the merchant when I entered the map, I was able to move into that space normally before starting the fight. Also there was no mention of him getting damaged in the log, the part I attached was the only reference to him at all.

It does seem to be an isolated incident however, as the other characters I've gotten there with have completed the quest normally.