"Can't verify subscription" error when trying to sign into Max

Max is included with my wireless plan, and it says so in my profile info and plan details on my AT&T accounts page. Whenever I try to sign in/connect provider, I continually get the same error message: "Can't verify subscription." I have not changed my wireless plan and I have always had access to the service previously known as HBOGO, HBOMax, and now just Max, until the last few days. I previously had a subscription to DirecTV stream which I cancelled. Calls to customer support to both AT&T and HBO have proven fruitless at this point. 

In addition to contacting customer support over the telephone, I have:

Cleared my browser cache

Uninstalled/reinstalled the Max app on my Roku device

Signed into AT&T.com as well as Max.com in a separate browser

Reset account password, twice

And yet, NOTHING has resolved the issue

Additionally, I am finding, as I'm sure many customers with the same problem have found, that this is a known error (according to the AT&T phone support representative) and that there appears to be a multitude of other customers experiencing the same issue and have found no solution or relief from anyone associated with AT&T or HBO/Max. It seems to me that this is something that should be addressed by one provider or the other, if not both. 

Maybe someone can provide some help?