Has anyone met the occasional rare bug in which the boss of a quest doesn't correctly spawn in within the past few weeks?
I encountered it a few weeks ago. Primarily in low level, ziggurat-based quests: Rats, Bats, Chamber, etc.
A little while ago I encountered quite the opposite doing the Chamber of the Marching Dead - only the boss, and one poor lonely zombie spawned. This was a couple of weeks ago, however.