Can't delete/add or see any entries in one Google Calendar

Question

I use Google Calendar on a regular basis, and somehow one single Calendar I created is now empty.

I can't add entries to this calendar.

The settings also seem very different from the settings of other calendars:

I also can't delete the calendar (the option is just missing):

I recently shared the .ics link to this calendar with a coworker. Could this have anything to do with the missing entries?

Answer 1

The issue has resolved itself. The calendar is now back and working normally.