I know this is 2 years old thread.
But this problem has been occurring since 2013 and even today.
You can't rule out the internet problem, but this happens to me all the time, for several years (in fact since Directv came up with iPad app) and I have pretty stable internet. though I could find a solution here. But apparently no, I guess.
AFAIK, the only way to solve this problem for me was that close the TV window and reopen. Or force the app to close and restart. Pretty annoying.