I've just gone in and
now I can see a lot more options!! It's like calling in a tradie and not being able to replicate the problem when they're there... I swear everything else was the same...
Thank you
EDIT: Actually I lie, there was one change. Just now I selected one-way, and was able to get a lot more QF options. yesterday I did return and had only one. I've been able to reproduce this.
Is this an 'undocumented feature'? A one-way Y flight will be less than the credit, I doubt doing J will be worthwhile and it looks like I can't get the flights I want as a return?