Yeah it does. It’s a migration that should take only a fraction of a second, so I didn’t put it in the “deferred migrations” section, I just put it in the normal section that’s done immediately on launch. But then mysteriously it’s taking multiple seconds! On my phone it felt like maybe 10 seconds. But for some testers it’s been long enough that iOS has terminated the app 
So I’ll be sending out a quick new build today, moving that migration to the deferred/delayed list, so that it can take its time, doing its thing after app launch has finished.
For this one, this is probably the weird “timeline subsystem gets jammed up” bug that’s mentioned here. I explain the background on it there, and yeah unfortunately it’s still present in this new build. Hopefully I’ll pin down the naughty code and get that one fixed soon.
If you see it happen, you can confirm it’s that problem by doing into the debug view and seeing the active operations list grow, with some tasks ending up sitting there incomplete for up to minutes. Backgrounding the app for a couple of minutes should resolve it (though I’m not sure why - this one’s being sneaky, with the real cause hiding from me!)
Yeah that very “debug” looking “timelineItems.isEmpty” or whatever is… not great UX 
I need to change that to actually explain what’s going on, at the very least. Either “there’s no data” or “I’m busy processing, brb” or “something else is going on”.