Wanted to thank everyone for the advice in this thread. Had this issue this week and took a few calls to AA EXP desk and they reissued tickets (exchange) twice to get this fixed. Etihad finally sent me proof that we had 1x 23kg checked bag each included with our ticket (only economy from MLE to AUH).

Oddly enough, pretty much all the EXP agents (even concierge ones) had never heard of this issue before with Etihad. Luckily, some of them were willing to make calls to look into it.

This thread proved to be extremely helpful when explaining to them what needed to be done (which I still find interesting).

Thanks all for the help!