Saaver award sounds like AA, which treats awards differently from QF issued awards. Both have algorithms to determine allocation, and in past years pre-covid QF had lots of cancelled awards (as people booked it 1 minute after midnight a year out in order to get an award) and these often did not go back into award inventory -- for F and sometimes J awards, even when there were empty seats. QF often flew with empty F seats 20 years ago, rather than offering upgrades much less awards. So it isn't just how full the plane is that affects whether awards go back into inventory. AA would often make awards available on partner airlines, when they had dedicated inventory (I think this is no longer the case).