I was actually able to resolve this by removing all tags except one, then going back through the google home app and adding the Openhab service. It connected successfully, then I just asked google home to sync devices. Now I can add the rest of the tags back again - although I noticed google says ‘error syncing openhab’ if I don’t have a name for the switches like this:
Switch HutchLight "Hutch Light" ["Switchable"]
