OK. I'm having similar problems. I had a P-6 error message, didi the 3x,2x etc. now I get a P700 error code. Haven't seen any channels working since the Roku upgrade on 7/5. Roku LT model 2700. 2 of them. And both do the same thing.
When I get a p700 error I change to a different channel on the TWC roku app and then back to the origional channel and that usually resolves the problem.
Not a fix, but a workaround.