Just found out this has impacted my BA142 on 23rd June. I am booked to go in J and had pre-selected seat but now in MMB it shows the QR cabin but does not allow me to select a seat.
my corporate travel agent says that seats are only available for selection at check-in but this leaves me a bit worried i will be down graded to economy. Not sure if anyone else has same issue. I will update when I hear more