Thanks Jim! While working out how to do that (I’m a complete knob, and those objects are alembic baked so I was thinking ‘do I need to build a new scene?’) I tried a few things and it seems to be an issue with the cache I had on the Collision Deformer! I emptied the cache, hit play, it was very slow but I rendered a frame, and the deformations were there!! ???? On the down side, it took lots of tweaking to get it looking ok. Ended up having to lower the “floor”, which resulted in the alembics floating way above it for the second half of the sim. I’m putting this one on the back burner for now. But thanks for replying!