Help needed: Calenders won't sync (Sony Z1 Compact)

Hello everyone, I'm hoping one of you can help me cause so far on other forums I've had no luck.

When trying to sync calendars to my phone, they show up when selecting them, but then the appointments don't actually show up in my calendar (regardless of the calendar app used). Then the next time I look in the calendar selection, there are no calendars present. At that point I have to restart the app and the same thing happens all over. I've already tried to clear cache etc but that had no effect.

Does this sound familiar to anyone and is there a fix? I love this phone but this makes it almost unusable for my needs.