This may be related to the recent myopenhab outage. Yesterday, my system thought it was connected, but didn’t work until I restarted the cloud connector.
You don’t need to restart openHAB, just go into Main UI, click on “openHAB Cloud”, and click the “Save” button without changing anything. Saving restarts the connector, and you’ll see that in your log.
After doing that, I asked Google to sync my devices and they started working again.
If you’ve changed nothing and GA stops working, you should generally start by checking the community to see if myopenhab is down. See my post from the recent outage for some tips.