Have you tried restarting the ATV? It sounds like its lost the user id for the app store. Also make sure you’re still logged in to the same user ID that you subscribed with.
I’m guessing you may have just updated the tvOS since they released one recently. That may have scrambled things that a restart would fix.
Then maybe sign out of and back into your account for iCloud and the app store on the atv. I’ve seen in the past where James has recommended this and it worked for others that Infuse didn’t recognize as a subscriber in the past.
Edit to add: Here’s one of James’ posts about that
You say Infuse Pro shows as a purchased app, is it the version 6 pro or the version 5 pro? Also, you said you’ve been subscribing so you should be able to see your annual subscription in your account info for the Apple app store I think. If you have a purchase for pro that’s a different download than the free version that you can subscribe to for pro.
You can check your subscriptions and make sure it still shows in your account following the Apple users guide