Missing channels on Roku 3

I have the starter tv service with HBO and STARZ along with a cable card setup with hdhomerun prime. I have 2 roku 3 and an xbox in different rooms of the house. A week ago I turned in my cable set top box to save some money and now I'm missing cnn and tnt on that twc app. When I try to view the channels on my pc in says subscription required even though I can watch those channel on my pc or xbox using windows media center just fine. I can even run the cable directly into my and tune into those channels with no problem. TWC say I can't view the channels on the twc tv app because I need a set top box. Why do I need a set top box for just those 2 channels? Isn't there something that tells that twc app what channels I am allowed to watch. Why is it that I can watch all the other channels that i am paying for with no problem and something as simple as cnn and tnt there is a problem.