Hi devel.bmad,
We have not heard back from you in a few days, so we are marking this post as Resolved for tracking purposes. If you are still experiencing the issue you reported, please respond to this message with additional information and we will offer further assistance.
Thank you.
Actually, I haven’t solved the issue, but I cannot reproduce the problem in a simpler setup, so I cannot really file a useful bug report. In any case, the problem is not just linked to the LightmassImportanceVolume, the all scene is kind of unstable, also slightly changing light or other objects may lead to similar results.
Just for debugging purposes, where is the swarm cache in UE4.5 on mac? it used to be in UnrealEngine ▸ 4.5 ▸ Engine ▸ Saved ▸ Swarm but I cannot find it anymore.
How can I reset the cache? previously clearing this folder periodically seemed to improve the situation.
~/Library/Application Support/Epic/UnrealEngine/4.5/Saved/Swarm