[Bug] Could not dismiss calendar notification

Thanks for your hint @Fellfrosch, but I doubt our problems have got completely the same roots or causes. It never occurred to me before, and simply restarting the phone did the job. But same as yours, it was a synchronized entry (was it on your side?) from Outlook. Maybe it was corrupted or changed by a subversive power. Will keep an eye on it. But I will not take as drastic measures as deleting databases, not just yet.

Yes all were synced entries from my Nextcloud. But if it is was just one of your entries than it's probably something different. I think the reason for my problem, was, that I deleted many times the calendar database because of calender duplication. Deleting the database left the reminders in it's place, so with every deletion of the database on the next sync there was a new reminder for the same event.

Alright, so either it's something completely different or just the same, only that you worsened it for yourself by deleting them DBs. :)