Booking Qantas redemption flights available/not available

Not sure if this has been previously answered. When searching for redemption flights. For example Singapore to London first class. It shows that classic rewards seats are available for a certain amount of points. When I click on that date it then says no seats availabile. This is on multiple dates.

Any ideas on this?

This may not completely answer your question, however I do know that Qantas have paused the use of Singapore as the stopover for Sydney to London for now. Instead it is using Darwin. Also, depending on when you are attempting to book, the A380s are only beginning to return to service in July of next year.

Something is going on because last week tried to book a business class redemption Singapore-Brisbane one way and they wanted 380,000 points!! Economy is about 29,000!