I have this problem with my animations, whenever I simulate traffic at first it's working fine. Then I go back into Openroads designer, do some modification and re-export to LumenRT and now all my traffic simulation was "drop" to singles car. The traffic still exist and if a select it again I can regenerate the traffic but the single cars that were drop from the previous traffic component don't get erased...
It'a a bug and need to be fixed but It's the kind of "feature" that could be nice to control.
Can you share any example files for review. Specifically a lumen file where the traffic is broken.
bentley.sharefile.com/r-rd78289214b742858