Thursday
I recently migrated my Google home and was able to see all my connected devices (e.g. my Nest, Hue lightbulbs, smart switches, etc) and setup a nice dashboard in Google home. I kept getting messages weeks later about migration so I did it again and I've lost the ability to include any of those apps in the dashboard. I can still control them with voice commands. Any suggestions about how to get them back and integrated with the Google home app?!
Thursday
Perhaps you should consider contacting Support (see below) to walk through what's happened in your situation. It's not possible to "migrate" your Nest Account to a Google Account more than once.
1. Go to https://support.google.com/googlenest/gethelp.
2. Select a category/product family, and type in a brief description of the issue, then click "Next".
3. Select your device from the dropdown, click "Other", then click "Next step".
4. Under "Resources", just click "Next step". (Clicking one of the listed links will bring up a Help page.)
5. Under "Contact options", choose to get a phone call or chat with the team, depending on availability in your country