When one books a flight on Virgin in Economy Delight, all of the seats show as "unavailable" if I am trying to select seats during booking. Should I just pick any seat and then the seats will show as open and available after I purchase? There is a window that pops up during booking that says something like "seats MAY be available..." but obviously, I want to make sure I get the extra-legroom "Delight" before buying.

Thanks!