Hi @DanMet
Welcome to the Sonos Community!
Are you able to play music to the Roam via the Sonos app? If so, we know Google is wrong.
First, I recommend you manually check for Sonos updates in the Sonos app - Settings » System » System Updates » Check for updates
Do you have any devices that extend the reach of your WiFi (mesh systems excluded)? If so, please turn them off and test Google Assistant on the Roam again.
Please let us know how you get on.