I installed the Hubitat App, but it keeps complaining that it can't connect to the Hub. But it is trying to use the wrong IP address and I can't figure out how to correct this within the app.
I fixed this by going back into settings, network and resaving my configuration. I was prompted to reboot the hub and then the app started working, however, while it shows the "rooms" I created, it does not show me the devices I added, even though I see them from the web interface.
The rooms in the App are currently limited to displaying switches and outlets.
And bulbs.
It isn't clear to me whether you are using the Device tab in the app, or a Dashboard?
As noted above, only certain types of devices work in Device tab, that is just a quick way to access commonly used devices, at least in the current iteration of the app anyway.
If you are referring to nothing showing in Dashboards, you need to build a dashboard, things don't just show up on their own. You have to add devices in the Apps menu, and then you can add tiles and so on.