Hi Arno,
Thanks for the sample application and your report.
Please, next time you report version 6.4 issues or bugs, please use the dedicated 6.4 forum, which we started for that purpose and can be found here. At the moment, version 6.4 is in preview/beta stage, and until it is release, commercial support is not provided.
Your problem is already reported and being worked on at the moment. Relevant issue can be tracked here. I added your application attached to a comment I made on the issue.
Palli