Just called SQ to check if their availability of ANA seats are the same as what I'm seeing on ANA's website.

On ANA's website, seats are open until June 27.
But when I called SQ to check their ANA seats, they can only check until June 13.
The number of actual open seats on certain dates however, are the same on both ANA's website and on SQ's system.

So looks like SQ is 2 weeks behind.