Can't control Tuya bulbs with Google assistant

[NeilEHome]

I have a simple set up - two nest minis (2nd edition) and 2 Tuya smart bulbs. These use the Smart Home app, which is supposed to integrate with Google Assistant. I can control the bulbs with the Smart Home app, and have followed instructions online from Tuya etc to link my account to Google Assistant, but it just doesn't work. When I ask Assistant to sync my devices it can't see the bulbs. 

Do you have any suggestions?

There are a few threads on here describing similar issues but none describe a solution 

[NeilEHome]

I have tried using the Tuya app instead of the Smart Life app, but similarly, even though it's linked to Google home, the devices just appear "Offline" in Google home, even though they're online and responsive within either the Tuya or the Smart Life app. At this point the kids are just using them as dumb lightbulbs. Pretty unedifying first experience of trying Smarten up our home