As the title says I can't get Withering bees to make skulls in an Alveary. I got them working just fine in the nether in an apiary with a skull on top, but when I switch them over to an Alveary with a skull on top they don't produce any skulls.

I think it has something to do with the slab staying seperate from the Alveary multiblock after it is formed, bees that require an item UNDER the alveary work just fine.