Anyone know if there is a specific setting to change after I have fractured an RBD Object, to cause the pieces to interact with a Fluid Tank?

If I pull the fracture (and wind that I have animated to test something) out of the tree, the regular un-fractured object hits the water and floats just fine.

Note: the Density on my objects was lowered to 150, but still without fracturing they float fine, so this isn't the cause.