Terra crab and Stinger mobs have exteemly slow spawn in spindalhalla crab room.

I have been sitting in the room for 30 minutes and 6 mobs total have spawned, I think their spawn was screwed up somehow. The last time I was in here they spawned normal rate. I have even sat here, waiting for the room to full up but there are only 2 mobs that have spawned after 15 mins