Want to spend some Avios to travel LAX-NRT next year but I cannot for the life of me remember how to bring up partner flight award availability on ba.com.

I could do it as recently as November/December last year, but all I get now is the British Airways doesn't have direct flights BS and then a 27 hour BA flight with a LHR stopover. I do recall it not being as simple as you might think, but I have tried literally everything I can think of today and it's just not happening for me. What am I missing?