Crystal Reports for VS SP26 Calibri Font issues

we are running an application on win server 2019 with cr13_sp26. we use simple reports with font calibri.

if we print the report, everything is fine.

if we export our report to pdf, everything seems fine, but it isn't. characters are stuck together like 'ti'. if you mark it (it appears as just 1 letter) and paste it into a simple editor, the character 'i' in this case is lost. next example: 'tt' --> single 't' and so on.

what i tried, (we already had this bug in earlier versions - it seems, it has worked much better in sp24!), the regkey:

UseCustomEncoding with dword 0. but nothing changes!

any suggestions?