I was talking with Aer Lingus in December (both on the phone and in their lounge in Dublin) on a separate issue but also concerning mileage awards on AAdvantage and they along with the AA Platinum desk confirmed that they were no longer part of the One World Alliance.

However, I would suggest you call the AAdvantage folks and try for credit since you booked it in August with the on-line understanding that you would get mileage credit. It can't hurt and who knows, they may annotate your account and give you credit.

Good luck