Hello Markus,
Thank you for your message.
Please make sure that your graphics card driver is already updated to the most recent version available. In addition, please make sure that the remote Host machine was restarted after enabling the Legacy Capture mode feature in order for the changes to be applied.
Last but not least, please try the solutions listed in
this troubleshooting guide and see if any of them might help to resolve the issue.
Let us know if this helps.