I wish Google would address this. From all the postings about this issue in this forum, it seems "assisting devices" are often problematic. Google needs to provide information on how to configure a new camera or doorbell without going through an "assisting device" when that avenue does not work.
I just spent over an hour chatting with Support and they ended up referring me to a senior resource, supposedly at least. I should receive an email in the next 48h.
I have tried every possible combination of on the wifi, off the wifi, on the mobile hotspot or not, restart the app, reboot internet, reset the thermostat... every single thing failed. Imagine how magical adding the device to wifi and just adding it to your app would be if I could do it again as I did 3 years ago!
I apologize for my late response and thank you for all of your patience while waiting for a reply. I can definitely understand how frustrating your situation must be, but I wanted to make sure that your issue was addressed. Do you still need help with this issue? I know that there's been a delay in response since you posted.
Please let me know if you need further assistance.
Same issue here. Brand new Google Nest Hub Max. Brand new doorbell. Can't get doorbell set up. Between this and the infuriating lack of practical calendar interaction on the hub. This stuff is getting prepped to be all returned next week.