Today I turned on my Roku Ultra and was only able to watch 2 local stations as opposed to my usual 10 or 15, whatever the basic cable package is. The rest tell me to subscribe. A couple days ago I returned my X1 box to comcast as I intend to use my roku instead. That's the only thing I can think changed. I didnt modify my plan, on returned my device. However it seems like others are having streaming channel issues as well so maybe it has nothing to do with returning my device.
use the my account app and sign in. under TV what plan and channel lineup do you see? if you returned last set top box and didn't arrange a no-equipment subscription there will not be channels to watch.