Can not log into HBOMax - says subscription is expired.

I've had this problem since the end of July and have spent hours on the phone with both AT&T and HBOMax support only to get nowhere. AT&T tells me to call HBO, HBO tells me to call AT&T. The last phone call I had with AT&T support was over an hour and ended with the AT&T Rep telling me to call back another day because he couldn't figure it out. 

I have the AT&T FIBER — INTERNET 1000 plan. I've had this plan since 2019, obviously with HBOMax included the entire time. HBOMax has worked without any issues until July 2022 when it abruptly stopped working and no one has been able to help. When I go to login on HBO and select "login with provider" I am redirected into an endless loop of "your subscription has expired". AT&T representatives have confirmed that I do have lifetime access to HBOMax, and I still have the original emails with that information. Apparently, on their end, it looks like I am having no problems. 

This is not a case of having multiple products or a family plan as referenced in some forum posts because I only have myself on the account and have only ever had internet through AT&T. 

I am stuck in the same loop of "subscription expired" with no way to fix it. 

I have tried accessing HBOMax on: a Roku TV, Fire TV, iPhone (HBO app and browser), iPad (HBO app and browser again), MacBook Pro (Safari, Firefox, and Chrome). I have cleared every cache, reset every password, signed out of every device logged into HBO, uninstalled and reinstalled the app, looked for the mystical HBOMax tile referenced by customer service reps and forum posts that I have never seen in my life, used every login combination imaginable-my AT&T ID, username, email, my account email, phone number, old passwords, new passwords, etc. I've gone through every suggestion on the AT&T help pages, AT&T forum posts, HBOMax help pages, even every reddit post on this issue. Nothing works. This has been going on for almost 3 months. What am I paying for?

One customer service rep suggested I pay for my own HBOMax subscription and try to get AT&T to reimburse me in the future. That's not happening. This is insanely frustrating. I've already wasted hours on what should be a simple fix. Clearly this is a known problem-posts go back almost 2 years on this forum and on reddit discussing this very issue. Why hasn't AT&T found a solution?