[1.7.3] Rak'Shor boss not generated

[Feorg]

Entering level 3 of the pride I only found a few rooms and a horror vault (and stairs to a sub-vault), which took up most of the level. The boss was nowhere to be found, even after digging out the walls. Maybe it had something to do with the vault being so big in comparison to the level size? The necromancer wasn't in the vault either, and nothing changed when I left and re-entered.