This bug has been around for a bit. It seemed to disappear for the most part in 796, but has come back.
Normally, one or two of the enemies are on the bottom walkway part with most of the enemies stuck in the pit area (which is walkable, but for some reason they refuse to get off). This also happens in some of my rooms that have a lot of water in them.
At least they've stopped spawning on non-water solid tiles (as far as I can tell)...
Lethality: Potentially makes player need to quit->continue (like when you're in a shuttered room with a piece of water you can't reach with your weapons and your enemy is stuck there...)
Enemies spawning on solid tiles(798)
I thought that the enemy placement flags were created partially as a means to circumvent bugs like this, therefore rendering it a fault of the quest designer if it happens.
However, if it is undesired behavior, I'm not going to classify it as "Not A Bug" until you get some developer feedback.
Guys, c'mon, this bug was posted one week ago. Let's be more eagle-eyed, shall we?
I did read that thread earlier. The difference in circumstance between the thread posted a week ago and the one posted here is that the enemies here are on a walkable pit. Although if that registers as being solid for an enemy, then it is indeed the same bug.
All the patterns the engine uses for pseudo random enemy placing can fail and when this happens the engine just dumps enemies anywhere using one of the patterns..
I'm pretty sure pits are considered solid for enemies no matter what. Sounds like a bug to me.