CLRegion Monitor stops working

I have set up an app to monitor for both geofence (CLCircularRegion) and iBeacon (CLBeaconRegion) monitoring for entry / exit events. Everything works fine for about a day. I get entry / exit events (generate a UNNotificationRequest to show a local notification) just as I would expect. I can run multiple other apps that would presumably force my app out of memory, with an entry / exit event launching the handler that generates the notification. But a day later I stop getting the events, or at least stop getting the notifications. I'm running iOS 13 on an iPhone Xs. Any insights into what might be happening?

CLRegion Monitor stops working
 
 
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