I just updated BOP on Curse (2.1.0.1585) and happened to notice a biome id conflict within the BOP config file. Both Visceral Heap and Seasonal Forest Clearing are set to 112. I discovered this when I found a Visceral Heap biome in the overworld within a Seasonal Forest.

Set Visceral Heap to 144 (which by my calculations is available amidst the many biome happy mods I have created in my custom mod pack via Curse) but this only caused the biome name to change. Perhaps future block generation for the biome id will yield the expected results.

I've confirmed that new generations of the Seasonal Forest Clearing are working as expected when the Visceral Heap biome Id is changed from 112.