Noticed the same issue a few days ago. Thought it would be temporary but doesn't look like it is.. the following is shown above the seat assignment:
This flight sector does not allow seat request in advance.
Which doesn't really jive with what's below the seat assignment:
The following passengers can request a seat in advance
Members of The Marco Polo Club and oneworld alliance holding elite status
All First and Business Class passengers
Passengers holding tickets on eligible fare types – W, R, E, Y, B, H, K, L, M, V, T
(Mine is also an 027 booking)