I've reported this issue about three times now. Finally got someone to call me from what appears to tech department management. She apologized and for the first time actually acknowledged the issue. AA has changed their backend payment provider for credit cards in January 2017. Unfortunately this created a loophole for those, who do not own a US issued credit card and/or do not have a local American Airlines website. AA is aware of this but frankly has no current scheduled (probably due this being a corner case) plan to address this, as its technically not their IT system.

I've once more received a more than generous amount of RDM as "compensation", although I've told her that his wouldn't be necessary as that is not what I'm after. And she even had to agree that it is quite ironic to provide me with RDM that I cannot redeem on aa.com due the issue existing in the first place