Unfortunately, it doesn't appear to be hardware or iOS version specific. So it is either related to some iOS setting we haven't been able to identify yet, or is a subtly corrupt version of iOS, possibly related to it being upgraded from older versions. A full factory reset might get it working, but to our knowledge no one has tried it yet (it may not work if the restoring process just reintroduces whatever settings/corruption is causing it). The stack trace shows it is crashing deep inside iOS UI rendering calls.
We have a potential workaround that we hope to privately beta test in the next few weeks. Appreciate everyone's patience on this – it is definitely a vexing bug for us to track down and work around.