Thanks @
Joshm300 ... think I’ve discovered what’s happening here .... on my previous reservation I had all personal details completed, seats assigned et al - obvs that’s not being flown now, but the new booking uses the same PNR but seems to not have all the personal details entered previously.
When I checked, our Exec club numbers weren’t there and, after I entered them, voila !
Seats now booked 👍