Hive fortress/breach defense instance crash replication

I've experienced instance crashes leading to a rollback in most hive fortresses I've attempted, and on occasion in maps where the breach objective is to defend. I believe I know how to replicate - placing a banner directly on top of Ailith during the defense appears to cause the instance to crash, I believe on wave pulse.

Explicitly avoiding placing banners close to her, I managed to avoid crashing the instance during a hive.

Explicitly trying to place banners on her during a regular map defense, I forced an instance crash near instantly.

My character is BiglyBannerman in ruthless keepers; I'm playing champion slams. I do not know if it was a specific banner associated or if any of them will cause the crash.