Why does device connections to Xfinity wifi seem very ambiguous?

I have four devices sitting on a table 10 feet away from my xfi router. Three of the devices can only see my 2.4g network and of those four devices three of them are connected to my 2.4g network, and one is connected to my 5.0g network. One of the three connected to the 2.4g network don't show up on the Xfinity app at all. The app isn't saying they are connected unknown devices it isn't asking me to assign the devices to profile. The app just doesn't acknowledge that they even exist. But the devices are showing that they are connected to my 2.4g network the other one is showing up on the app and does belong to a profile. Same as the one device that is connectedTo my 5.0 network. It shows up in the app and is assigned to a profile. The fourth devise was connected to the 2.4 network and it shows both as an option so I switched it to my 5.0 network and everything worked as should. Why are there 2 devices that are connected to my 2.4 network but I can't see them in the app anywhere? And why can't these same 2 devices even see the 5.0 network? So I could switch them over and see if the app can find them?