Some of my calendar just disappeared in Agenda

2 hours ago I linked some notes to the events in Work Calendar of my apple id. When I open Agenda 5 mins ago, the calendar just disappeared in Agenda and all my notes were linked to the day when there should be an event.

What’s going WRONG?
How can I find them BACK to Agenda?
Do I need to RELINK everything???

It sounds like Agenda lost access to the calendars, are you sure they are still available in the Calendar app? Does it help if you force quit the app and start it again? See https://www.imore.com/how-force-quit-apps-iphone-ipad

Yes restart never failed. It is fixed after I restarted it.
But I’m sure that everything in the Calendar is find, so I still don’t know what went wrong. Just hope this wouldn’t happen again. Anyway, thank you for your advice!

Ok, glad it got fixed, let us know if you hit it again.