This issue has been posted before. Xbox support suggested posting a new thread. Here are the details:
-I purchased the full season three a couple of months back. When the second part of the season recently aired, the posted episodes show no option to play...only to 'buy'.
-When I select 'buy' I receive a message claiming that I have already purchased the full season and this episode is part of the content. Of course it still allows you to continue to purchase regardless of that message...and still continues to fail if you cancel the purchase and re-start.
-I have tried deleting the app (windows 8 version) and re-installing. I have logged out and back in again. I have checked with tech support a total of 3 times since last week (same problem occurred then). Nothing works. Yesterday tech. support suggested waiting 24 hours. Been there, done that...nothing.
-I decided to go ahead and purchase the episode and try to get a refund later like I did last week. It works...but very frustrating.
If this goes unresolved I will definitely avoid xbox content in the future and not waste my time and money.