ARIS 7.1 Reports/attributes converts ÄÜÖ etc into ?

Dear All,

I have an issue with the German special characters like ÄÖÜ etc in ARIS Toolset 7.1 (okok .. I know it is a bit outdated).
Editing attribute in the aatributes window or running a report converts always these characters into an ?
(in the reports I am using ARIAL as font and the conversion happens with all type of outputs)

I am running my Surce pro 4 with the actual windows 10

Does somebody has an idea ?

Thanks

WOlfgang