Google Assistant with own openHAB Cloud setup not working


i have successfull installed the myopenhab cloud on my server, additionally i have installed the ifttt function which is working too.
Now i want add the Google Assistant module and here i have a Problem.
I followed this instructions :
up to this point

  • Afterwards please run the following command in the gaction CLI:
gactions test --action_package action.json --project <PROJECT ID>

everything has worked.
after the gactions test i received the following error (the changes to the mongo DB are made):

Pushing the app for the Assistant for testing…
ERROR: Failed to test the app for the Assistant
ERROR: Internal error encountered.
2019/10/10 10:49:39 Server did not return HTTP 200

if i Try to open https://myownopenhabcloud/openhabGoogleAssistant i will get this error: Cannot GET /openhabGoogleAssistant

Is there something missing in this documentation ? or have i do something wrong?

My owncloud server is runing behind a nginx Proxy is there maybe the problem? because there is no entry for /openhabGoogle Assistant

Thank you for your support