I still have a problem with the native eOS calendar app. By now, I have figured out that eOS will give me notifications of my events, bubt they appear approx. 2 hours after the start of the event. I even tell the app to specifically give me a notification when the event starts.
I think, that somehow my local time or somewhat related must be off, since that's the only possible reason I can come up with to produce such a weird error.
It might be noteworthy thatI disabled all other notifications, except for "calendar" and "other".
I made another post regarding this topic, but I have now found out that the problem lies somewhere else. I ask politely for someone to delete my older post (no notifications from calendar application), since it's not of any use anymore.
EDIT: I have noticed that the events are saved differently in and out of the calendar app, see test and test2 event in notification center and inside the app itself.