Possible caching problem, help needed

I’m using MEC Lite 6.3.0 and have a recurring event that I originally set for every first sunday and never ending. It’s a one-day event from 6-10pm.

Now I need to change things up and I want it to end on 1st of January of 2023 – which I then chose as the option. For some reason the events from January 2023 to infinity are kept, they do not disappear. Even worse, in the list they now show up as a multiple day event from let’s say 5th of February 2023 to 6th of January 2019 (past!).

Is there some kind of cache that doesn’t get overwritten? It’s not my browser and I deactivated the only cache plugin I was using which didn’t make a difference. Help!