Hello Sven,
We have now released a hotfix, we have now added the support for new date & time formats "MM-dd-yyyy", "dd-MM-yyyy", "yyyy-MM-dd", "MM-dd-yyyy HH:mm:ss", "dd-MM-yyyy HH:mm:ss" & "yyyy-MM-dd HH:mm:ss". Please refer to the below link to get more details about this hotfix,
Please get back to us if you need any further assistance.
Thanks & Regards,
Ram
ServiceDesk Plus OnDemand Support