I'm having the exact same issue. Can't see the episode on my AppleTV app on Samsung SmartTV, can see the episode on my AppleTV app on my phone and computer, but cannot watch the episode.
I called the Apple Support line that another commenter linked to and was transferred around a few times. The third person I was transferred to was "Technical Assistance" and had me screen share my phone, where I could show her the difference of the issue in the phone app and the SmartTV app. (Side note: Very interesting/creepy how they can see your phone, including your camera, with permission of course).
She saw the issue via my camera and AppleTV app, put me on hold, then said she had to transfer me to the media services team (my 4th transfer). Then that person said they can only check billing and subscriptions. She said there can potentially be an update happening that can take a few days for it to come back. She checked to see if there were any updates on Apple's part, because she felt bad that the person who had more power to help me transferred me to her. She put me on hold (by this time I'd been on the call, bounced around between agents for 30 minutes).
She asked me if my AppleTV apps were updated, and then said they usually update themselves. I logged out and back in a couple of times and the issue was still there. We double-checked my version (13.3.1) and confirmed it is the latest one.
She said the company (Showtime?) may have pulled the episode, but they (Apple Support) wouldn't know because Apple doesn't own the content. Suggested to keep an eye out to see if there is news on other forums about the episode itself.
So that was 40 minutes of my Saturday afternoon. You're welcome, all! :-P
UPDATE: I just signed up for a free week of Showtime directly on the Showtime website and I *CAN* watch Season 2 Episode 2 there. So this must be an AppleTV issue after all?