I am trying to use some old VS miles to book some VS award seats for family members and noticing some strangeness. This is a pure miles booking, not miles + cash.

When searching as a return LHR-JFK-LHR, it only shows one flight available for the return date. It is not an ideal flight time but if that is all that is available, then so be it.

However, the strange thing is, when searching JFK-LHR as a one way sector on the same return date, availability is wide open on multiple flights, including the preferred flight (the daytime one).

Booking as one ways is obviously more expensive in fees/taxes so not ideal, and the call centre was absolutely no help and refused to check the one way availability to see the discrepancy.

Is this normal for VS awards?