I want to update a cells header either based on an event, so looking for a special string, or through some other way to send in data from an API. This would be something that is unique to each day.

I have a problem with the calendar Ui not getting refreshed upon event edit/delete. I have a custom modal which lets me edit/delete the event and upon save, data is updated to the db and there is a callback to the calendar.refetchEvents() method. The events are fetched through ajax call i.e. events (as a function). I see that the data is updated in the db and the ajax request returns the updated data,
but the problem is calendar Ui is not refreshed always. It works sometimes and sometimes it doesn’t. By this I mean the Ui shows the updated data sometimes and I have to close fullcalendar view (modal in my case) and reopen again for changes to be visible. Pasting my code below. It’s the same code mentioned in the docs.