To update:

SQ called in response to the email and they have fixed the problem for this ticket. Now it is the same situation as reported by [MENTION=881270]flutterby77[/MENTION]. Seat availability has been expanded for this ticket (consistent with ExpertFlyer) and seat can be changed/selected with no fee.

Looks like this ticket was mapped incorrectly before.

On a side note based on this mapping, it would appear that in the new system, the trickled seat availability of the past for long haul flights is no longer the practice as all unoccupied seats are shown for selection at all times. I could be wrong on this based on this limited data but perhaps others who have traveled under the new fare class can confirm.