Abyss within map fails to spawn remaining monsters

Bug Report ID: #3593879447

Abyss fissure did not spawn all of the monsters as I was clearing it. Just this one last node (of 4 nodes total) seems to be affected. The other 3 nodes are sealed/closed (finished).

0 monsters remain in the area including the map boss - pretty certain this is a bug. Combed the map for monsters just in case.

Not sure if it matters, but this is a T2 rare map - Wetlands tileset.

In case you're curious what it looks like: