I was recently working on a RBD simulation with packed objects and I noticed that after a few frames the geometry would stop rendering in arnold. The strange thing (at the time) is mantra did not have this issue. I added a attribute/group delete to delete all the extra attributes, but I was still having the same problem. This issue would go away if I disabled my pop drag/pop spin drag forces. After messing around I noticed that turning on my drag forces caused some of points to have NaN values when the simulation collided with the ground. After adding a clean sop and checking remove NaN’s, the geometry seemed to render fine. If any of the points had NaN values, arnold would not render anything. While removing the NaN’s is one way to fix the problem, I found another solution: Increasing the substeps in the bullet solver until there were no more NaN values. Both these solutions can be used hand in hand to make sure no NaN values make it to arnold. The pop drag/spin drag (in my testing) only created NaN values for packed objects (with low bullet substeps). If I use those drag nodes on proper pops, the issue is non-existent. The issue is particular to bullet solver.