Local Calendar events disappeared

I tried to remove a repeating calendar event from the unsynchronized **Local Calendar** account using the stock calendar app1. At first I thought that *all* calendar events were deleted (not just the repeating event), because the calendar was now completely empty. But then I realized that I could still export all calender events using Calendar Import - Export . And sure enough, inspecting /data/data/com.android.providers.calendar/databases/calendar.db revealed that all events were still there. I tried the following to have the events displayed again in the calendar app: * Checking the proper calendar account was selected (it was, there is only one) * Using another app: DigiCal also displays no events (which it previously did) * Resetting the calendar app * Restoring the calendar app from a backup * Clearing the cache (not the data) of the *Calendar Storage* app that provides the database file mentioned above * Manually adding a new event works, but all other events are still missing. Exporting all events again now also includes this new event. Nothing of the above fixed the problem. I could purge the data from the Calendar Storage app, clearing the DB and importing all events that I previously exported. But I'm hestitant to do so without understanding what's gone wrong and how I can properly fix it so it won't happen again, and I'm not sure this would even work. What's going on here? How can I have all the events displayed again? 1 I'm running Xiaomi.eu's MIUI 12.5.2.0