Same here.

Had an award and one segment got downgrade from F to J. I am able to change online to another flight that has F a few hours later - keeping connection legal. Errors out at purchase page. Tried different credit cards.

I know the flights are available through EK site and QF. I always search for at least 2 available F seats on the QF site that translates to one on AS.

Have no idea what is going on.