Abyss keeps spawning mobs but no experience gained

Bug report reference number: 3,278,968,099.

Not sure how to give more information about this bug. The abyss kept spawning monsters and the hole wouldn't close. The hole went to a corner in the Tower Map, picture is below.

I also had this bug a couple of times. After completing the last pit, the mobs keeps spawning everending, but just a few normal monsters every few seconds. I think it was both times after defeating a stygian spire. Maps were Malformation and Crimson Township.