Without knowing the OP's specific routing and number of days before departure I can only relate my own experience with this. AA loads inventory for booking at, I think, 330 days prior to departure. The day before this, when it is not bookable, EF will show the inventory, including Z, with all 7s. Your first thought is "wow, lot's of award seats!" only to find out they don't show on AA.com or by calling AA. The next day when the flight is open for booking, poof!, the 7s are gone and replaced with "real" inventory levels perhaps Z=0. This has been my experience with the Hawaii flights. YMMV.