Wow, so this issue / potential solution seems to fit my case exactly.
Right after I typed my previous post, I found an actor that players can spawn which has a Niagara particle effect set to Auto-Activate from the “Portals_VFXPack”. I’ve added it very recently, so the timeline fits. I even have a screenshot from a player attempting to spawn that actor while crashing right at that moment! The particle effect that was set to Auto-Activate is the small purple circle that just got created:
It will take some time to test in my case, but this seems very promising!
@Sononeo Thank you so much for posting your potential fix!