XFINITY app does not show connected device

Over a month ago, I was offered a free upgrade to a new modem. Since the upgrade, I can connect to the internet but I have been unable to see the new modem in my XFINITY app - I can't view any internet settings, can't see any connected devices, can't change any internet settings. I can't even change my internet name or password because the device is not showing in the app AT ALL. And the support through the online chat says they can't help me change it due to security issues.

I have been contacting customer support through the support chat for a month and have probably talked to more than 10 different support agents. Each time, they tell me that there is an issue and that the device is not correctly connected to my account. They promise me 100% that this time the issue will be fixed - the issue is never fixed.

Today, I contacted support again and they immediately told me to call Xfinity and ended the chat. No matter what option I choose in the automated menu through the phone, I can't get an actual person on the line to help me.

1) I have already restarted the modem 10+ times

2) I have already uninstalled and reinstalled the app

3) I am logging into the app with the correct email address

4) I am able to connect to the internet using the name/password someone set up for me over the phone

5) Still - nothing is fixed - the app does not detect my new device.