I just signed up to Expertflyer for the 5 day trial to give it a go and to see how the seat maps for my upcoming CX flights later this year look like.

I was thinking that as there is still some 6 months to go until I fly, and availability is showing as "9" in all classes that there would be plenty to choose from this far out but I notice that the site is showing the majority of seats in Y as 'blocked'. The same seats also seem to be blocked or available for the same flights either before or after my date of travel.

Does this mean that CX is just holding off on releasing these seats for pre-selection until nearer the date or are they restricted to being assigned until check-in.

Of course the seats I was thinking of are blocked.