I have been trying to add a new family through Google Home. I followed all the directions and when the new person attempts to join in Google Home (to accept the invite), we keep getting that the link is not valid.
Her nest app recognizes the invite is pending as well, but when you click to join, the same message is received.
Thanks for reaching out — let's check this out.
A few questions: are you using an Android or iOS? Are you inviting a regular Google Account? You can't invite the persons with Google Workspace (G Suite) accounts and Google Account for children under 13 (or the applicable age in the customer's country).
Try uninstalling and reinstalling your Google Home app. Try also using a different phone to isolate the issue.