HBOMax streaming stopped working - "Your HBOMax subscription through Xfinity has expired."

HBOMax streaming no longer works.

I have subscribed to HBOMax through my Xfinity account for about a year. I have a Tivo with a Xfinity cable card, and can see HBO on cable no problem, my bill is current and paid, I haven't canceled HBO. Last year I also used the HBOMax app on my AppleTV box to stream HBO shows, no problem, and even did it this fall, up until a month ago. Now I can no longer stream using the HBOMax app on my AppleTV, although I can see HBO on cable (my latest bill still shows a current HBO).

I signed out on my AppleTV, and and when I try and sign in to the HBOMax app on my Tivo, it asks "are you a subscriber through another provider?"

When I answer yes, I select "Xfinity" as my provider, then it asks me to sign in to my Xfinity account, which I do. Then it takes me to a page on the Xfinity web site that tells me about HBO, asks me if I want to subscribe, etc. No place to acknowledge I am already subscribed through Xfinity, even though I can look at my account and see that I am. No way to return to the HBOMax app, and no way to see HBO content.

Same thing when I try to sign in to HBOMax on the web my computer - signing in through provider takes me to a Xfinity web page that trys to sell me HBOMax - even though I am logged in and can see I already subscribed to it.

At one point in frustration I created a HBOMax account, so there I also can sign in. If I choose to sign in to HBOMax directly (ignoring the "sign in with a provider" option), on my AppleTV or on my computer, I can sign in but it says my HBOMax subscription through Xfinity has expired.

How can I get this to work again? My guess is Xfinity needs to send my subscription info to HBO, although why they lost it is beyond me.