Problem with time zones and events on Mac

Hello, im using the newest version of the emclient beta for Mac and so far things are really great, except for one thing: My existing events in my calendar show up correctly, but when I open them, they are in the wrong time zone. Im living in Germany but for some reason the time zone is set to EST. I checked the Mac time, that seems to be fine. How can I fix that?

Probably similar topic here.
Creating an event on a Mac everything looks fine.

If participants are invited that use  Outlook, their Outlook will state the the time zone was somehow “corrected”, and the event in the other users’ calender is one hour off.

We tried different settings (Mac OS: time zone automatic, or manually set; eM Client event: set not specific time zone, or do explicitly set the time zone), no difference.

It that matters, the server both users are on is an IceWarp server.