In this big room in Cave 1 (Has it a name? Lava room?) I noticed two issues (but I don't know if these were also existent on the official servers).
(1): Immediately after entering the room, I can target and attack monsters, but they don't notice that I entered the room (i.e., they seem to think that I'm still in the safe corridor), so they don't attack:
(2): When standing on this round platform in the middle, this monster didn't try to approach me. Instead, it was going around in a circuit all the time (hard to see on the screenshots, but I stand right there for 1 minute without getting attacked):
(1): Immediately after entering the room, I can target and attack monsters, but they don't notice that I entered the room (i.e., they seem to think that I'm still in the safe corridor), so they don't attack:
(2): When standing on this round platform in the middle, this monster didn't try to approach me. Instead, it was going around in a circuit all the time (hard to see on the screenshots, but I stand right there for 1 minute without getting attacked):