This has been happening for a while on a lot of my tvOS apps, mostly games though.
I think tvOS' marketshare is not high enough for many app developers to justify supporting the platform.
Many tvOS version games that I have invested $ in no longer work. Last summer, one of my favorite games, RISK, by SMG Studios, was pulled from the App Store. A message pops up saying that you have to update the app, but clicking the button goes no where since the app was pulled.
I contacted the SMG support team, and they said they are having issues with supporting the tvOS version of RISK because of the lack of SDK support and third-party plugins, so they had to pull the app.
Many other apps in a similar boat. Apple doesn't seem to care too much about the ATV and tvOS, so I don't blame developers to stop caring as well.
Just sad...