Isn‘t the availability logic the same as for row 9 on the other 77W models (=the ones with P class)? Row 9 window seats are opened up some time between 72 and 48 hours before departure, and is then available for everybody. I think they are considered bassinet seats and cannot be selected by anyone travelling without an infant, not even elites, before. At least that is my own experience. I never managed to pick 9A or 9L outside a (roughly) 48 hour time window.

Maybe the attribution logic for the no-P 77W is different?