On AA (as AA) O class fares earn everywhere but:
Originally Posted by American AAdvantage
** Tickets between North America and Latin America booked in O are not eligible.
This is a relatively recent change; some O and Q did not earn AA miles previously. I suspect if you contact AS they will tell you the last bit is probably a misteak.
FPO is in the Bahamas, not in Latin America, so again if you check with AS, I am going to guess you would only have to upfare if you are traveling to / from
Latin America; otherwise, your ticket should earn as advertised. I'd certainly call before paying to upfare.
(And here I thought only AA sometimes failed to update every bit of its website and T&Cs.)