XB7 - Can't make changes in app, not broadcasting 5Ghz band

This all started when I upgraded to Xfinity Complete with the battery backup option. I already had an XB7 at home, but I figured I would see if the "new" one had updated firmware, which it did not. I have had my current one for at least 2 years and it has firmware 7.9, whereas the "new" one has 7.6. Why are modems shipping with outdated firmware? Anyway, not the point. I didn't want to go backward on the firmware, so I reactivated my original modem, which is where all the problems started.

Before all this, I had both my 2.4Ghz and 5Ghz bands broadcasting separate SSIDs with no issue. After reactivating it, I only had the 2.4Ghz band. I checked the Xfinity app and both bands indicate they are broadcasting, but no device sees the 5Ghz band, nor am I able to connect to it if I manually configure the connection on the device. I attempted to login to the admin page via 10.0.0.1, but I forgot the password. At this time, I performed a "factory reset" on the modem, that only halfway worked. It reset the user/password and I was able to login, but all of the network settings remained the same. After I was able to login, I checked the Wifi setup and noted that both the 2.4 and 5Ghz bands now had the same SSID, with "2.4" appended to the end of the name. They were also both showing up on my devices at that point, but that doesn't matter because with identical SSIDs, you can't discern between the bands. I double checked in the Xfinity app, and it showed that they were both active, but still showed separate SSIDs. Also of note, is that the app showed the encryption type as "unknown" but in the admin page, it was WPA3. The app only has one option in the encryption dropdown, and that's WPA2. I tried multiple times to make changes via the app, and every time it gave me a generic "something went wrong" error and would not change any of the settings. I did note that the support page for the XB7 says that the bands are now managed automatically.

I believe what this boils down to is that when I received my original modem a couple of years ago, I was able to do setup via the admin page. Now that the features I setup are no longer an option via app configuration, the modem is basically bricked. I was going to ask about an upgrade to the XB8, however that one has also been dumbed down significantly, and setup options are severely limited. It's looking like I will need to buy my own equipment if I want to have separate bands again. Could I get this confirmed by a rep?