Nextcloud calendar freeze and nit loading

Hey I am facing a problem for a longe time now,
abd cabt fix it.

Every once and a while tthe nc calendars freeze and are not loading after reboot.
The circles are turning but the items are not loading.
No changes while updating nc or the calendar app or the underlying debian.

Sometimes it works after a reboot, sometimes several reboots are nessesary, and its working again.

Sync is nit working without errors msg, because the Connection IS working.

Anyone who can tell me how I can figure out whats the Problem?

Thanks a lot

Open the developer tools (F12) and paste what’s shown in it.