Board Thread:Bug Reports/@comment-30645975-20161212220412/@comment-25330335-20161212221929

In regards to the mob spawning, that is an intended feature. It's designed that way to be more immersive.

The troll hoards spawning above ground is an issue with what block the hoard spawns on. I'd assume that all the places you found them were bare rock. Really that condition should be more complicated. I will leave this on the bug reports board, but edit your message.