I have rolled back Open Composite to an August build. It works again. but not sure if I am allowed to share this dll version.
Edit:
here ist the official link
https://ci.appveyor.com/project/ZNix/openovr/builds/44737351/job/3gqqsloajd7rl87y/artifacts
download 64bit artifact and replace "*\OpenComposite\Runtime\bin\vrclient_x64.dll" with the new one... don't forget to rename and backup old one
if you update, it overwrite the dll again