I’m using 5.5. Not too keen on moving to a new engine version as I was hoping 5.5 would be stable enough to build on, but the more I make for my game the more issues I run into.
I found a work around for this issue though. It’s not a fix by any means, but I’m able to at least make progress. Basically I just need to close down the sequencer when I hit the Play In Editor button. This prevents the crash from happening but it’s a bit tedious to have to continuously close and re-open the sequencer when testing and tweaking animations. Otherwise it seems to work fine now.