Hello Thorsten,
Thanks again for your answer. We of course understand the issue with the hotfixes, thanks anyway for having checked. We will wait for the next release and will maybe migrate to 7.9 (I'm currently checking with our system admin). I leave the forum thread open and will mark it as resolved when we will get the new version and everything works fine.
I would like to thank you once again for your amazing support: if you once come to Switzerland, let me know and we will invite you to discover the swiss gastronomy (with a heavyweight cheese fondue). ;-)
Best regards,
Christophe