Dear Lukas,
Thank you very much for the question!
This was one of a known issue in the first release of Archicad 23. We fixed this issue in update 1 of AC23 already. At the moment, update 2 (5005) is available for CZE. Please update Archicad to the latest version in order to get rid of this issue.
Please let me know if it helps. Thank you very much!
Best regards,
Minh
Minh Nguyen
Technical Support Engineer
GRAPHISOFT