Super late reply but have you scaled the hard constraints to zero? Just setting the rest length to zero will mean the constraints will all try to return to zero length as they have an existing length.

Hi, I'm getting some very weird behaviour with some of my particles that collide with my VDB. They should come to rest but a small percentage don't ever stop moving. The collider is a VDB created using the Collision Source node and represents the original RBD pieces converted to a volume. I've tried using Auto Sleep and various other methods but these same particles just never stop. In one of the videos the purple colour is the active particles and the red are the sleeping particles. I've upped the substeps in the pop solver to 20 and they sill move. Any advice would be much appreciated. POPNeverStopsFlipbook.mp4 POPNeverStops.mp4