Sometimes there is a glitch at a particular store. For example, I use my AMEX Blue Cash Preferred to get 6% cash back at grocery stores. One local grocery "chain" has three stores. I get my 6% cash back at 2 of their stores, but not at the other. I contacted AMEX about the problem, but it never got resolved. Fortunately the store at which I did not get my 6% is farthest from me, so I just don't shop there any more.
I have shopped with my AMEX at many different Whole Foods groceries across the country and all of them have coded as grocery. So, my guess is that the problem is with your particular store in Birmingham. You may want to call AMEX again and see a different CSR can help you.