In SIN (AC020), the waiting area is *after* the agent desk (which is immediately after the gate security). This means everyone is "boarded" when entering the gate area. It would seem that YBYL doesn't exist here. My upgrade hadn't cleared yet and the agent insisted I scan my BP anyway. The computer rejected the BP and was asked to sit down to the side. A few minutes later, the upgrade went through and I was given a new BP and could head to the plane immediately.

5 seats available in J with 7 people upgrading from PY.
6 seats available in PY with 5 more available if the above upgrades go through. I was #1 and #3 (companion) on this list.