Glad that worked for you. You could try these things and see if that helps.
There are a couple things to try, but I think this is a known issue with the OS.
Check for an update of your device and see if there are any firmware updates on the Roku.
Check the channel store and see what the status of the NFL app is and see if you have the option to add/install, or able to move to home screen, etc.
Do another system restart and see if the app shows up.
Check to see if you can see the app on your Roku phone app.
Although I know you have done this already, but you could try uninstalling the NFL app, system restart, which should clear the cache, then install the NFL app again and see if that gets it to show up. Make sure you scroll to the bottom of the home screen to see if it added there.
You could also try a factory reset, although I know that would be a bit of a pain, or you could wait a couple days and see if the issue fixes itself and the icon shows back up.
