Partially applies to Dusk of World map at lvl 35 - sometimes it disconnects, sometimes it loads (1/2 success rate). Seems like those maps that have custom line-ups for coop give a problem here.
For some reason the healing effect from "Defending Shrine" mission carried over to the next mission, Swamp King. Both were done in co-op which suggests bug is related to that.
Clearly there's a bug that somehow allows that effect to be snuck past the erasing after the mission.
Effect only appears on the part of that map. Not sure if it's related to shrine at all since I got it 2nd time coop-ing with someone who didn't do the shrine with me prior to that.
"Supplies on the run" mission at map level 7 in coop spawns monsters at lvl21 instead of lvl10. Reproducible.
Blood Cornelias on all maps below level 10 are vastly overpowered and way stronger than any other monster in the vicinity. They should either get range or damage reduction there.