Are there any tips and tricks on using the Qantas multi-city search?

I have been accruing Qantas FF points for some time now and had planned to use them to book a trip to Europe next July. This is my first time using points and from my research I had been using the multi city search on Qantas to find flights.
I don’t have a lot of flexibility with my dates, I couldn’t find anything suitable for MEL to Florence, so purchased flights.
I am now searching return flights. I had considered coming home via LA, using the multi city search (London - LA, LA-MEL) I could find a direct flight from London to LA with British Airways, but then could only see China Airlines flights via Taipei from LA to Melb.
When I did a single search for LA to Melb (on the multi city search) I could find a direct Qantas flight, but when I go back and try and put the two flights together in the multi search, the LA to Melb flight doesn’t come up as option.
Can someone explain why this is? I feel I may be missing out on flights by not searching correctly

Hi @natcrosby,
I’ve had that happen to me before as well when looking for flights between Australia and the US. I’ve been told this happens because it means reward flights aren’t available on that route, which is why it wont show up when you’re looking for point flights but will when you search for paid flights.
If you have any flexibility from where you depart the US, I found a flight that was Dallas/ Fort Worth - Melbourne via Tokyo. It only added about an hour on to the flight and I preferred to layover in Tokyo than in Sydney.
Good luck!