Can’t go further with mastery part 3 (winning against easy AI). I won from easy - very hard and still don’t get the mastery part granted. Problem only shows at abbasid so far.
Was the win in a skirmish or multiplayer?
Did u save at all?
How long was the battle and did u get a disconnect notice during or after the battle?
Try restarting router, doing it in skirmish, check exact wording (im unfamiliar with its exact wording), beating it fast as possible, not changing any of the game settings- resources/starting age etc…