That’s a different crash. When these crashes occurred, was it during Play in Editor? They appear to be a networking/replication crash; is this a Multiplayer game?
This crash is also already in our system (UE-16587), and it appears to involve seamless travel. Try disabling that in your GameModes and see if that crash ceases.
We have some reliable reproduction steps, but I’d like to hear any additional information you have so I can add it to report. I’ll post here when I see any update on that.