So when I got to floor 12 there was... nobody. Like i checked five or six rooms and every one was empty--no monsters were spawning, until I eventually found a single Thorling. I'm not even 100% convinced it IS a bug, because it fixed itself when I went upstairs and back down--new rooms I've gone into have had monsters now. I don't know, is this a known random issue that can be easily resolved, some very strange RNG behavior, orr.....? (I'm on windows 7 64-bit if it does matter)
Very strange RNG behaviour. Most of the time monsters are spawned purely by the RNG, and it is possible for it to start hiccuping and doing weird things.