For anyone coming across this, I believe the issue may be that I created a task list instead of a calendar. Even though these appear as calendars, you’ll be unable to add any events to them. I think I may at least open a bug report to see if we can convert task lists into calendars.
See also:
- Transform Tasks list in calendars
- Convert Task Only Calendar to Full Calendar
- [Reddit] Can’t add events to calendars that were created from a task list, how to fix?
- [NC Deck, unrelated?] Create a setting that allows cards to be exposed as events rather then as tasks in webdav. · Issue #2629 · nextcloud/deck · GitHub
- Convert existing calendar without task list to calendar with task list · Issue #2627 · nextcloud/calendar · GitHub