Google Request Syny Failed

I am getting this error when I call the google_assistant.request_sync service:

request_sync request failed: 400 b’{\n “error”: {\n “code”: 400,\n “message”: “Request contains an invalid argument.”,\n “status”: “INVALID_ARGUMENT”\n }\n}\n’
07:50 components/google_assistant/init.py (ERROR)

I also get an error from Google Home if I say sync my devices. It syncs the google native devices but fails on my test project.

It still controls devices in the test project though and otherwise works perfectly.

Any ideas?