I'm on a Xiaomi Max 2, MIUI 8 (Android N 7.1.1 NMF267).
Google Calendar sync works when I choose "Refresh" from the top right inside the Google Calendar app. But a few hours later, the calendar shows up empty. When I click "Refresh" again, it works again. And so on.
This seems to be a widespread problem judging from online complaints. I'm savvy with computers and phones, and have tried every fix mentioned online. Including clearing cache in the Google Calendar app, uninstalling it, clearing cache in Google Play Services, and re-installing the Google Calendar app.
The Google Calendar Sync Android Docs say to "make sure that Calendar storage is turned on"
HOWEVER, on my phone, Google Calendar doesn't even ask for App storage permission. It doesn't show up below in the list of apps asking for "storage permissions" (Note: the "Calendar" below is MIUI's internal Calendar app, not Google Calendar. MIUI is Xiaomi's Android skin):
I'd appreciate any suggestions on resolving this issue.