Game crashes when loading first battle of faction event

Platform, device version and operating system:
Iphone 8+, IOS version 14.4.2, Game version 5.4.0r26696

Screenshot or image:

What you were expecting to happen, and what actually happened:
I finished selecting a team and hit the button to start the fight. Game sends me to my phone’s homescreen. When I start the game again, the battle is lost and I can only leave the delve. Wasting a sigil.

How often does this happen? When did it begin happening?
This is the first time it has happened to me.

Steps to make it happen again
Starting a regular delve didn’t crash the game. Don’t know what makes the faction event special. And I don’t care enough to try again, I’m done with the event for today. I’m going to make sure that I can actually do the new faction this Friday, before I spend gems on it.