Edit: it seems that just while writing this post that seat disapeared from CX, BA, etc availability. However I'm still curious on if the original issue where I could see availability for that flight, checking multiple times over the past week with it available. From your experiences was that most likely agent error and it was available, or was it likely that it was never available to begin with?

I'm trying to book a OneWorld award to get myself from SFO to Doha next month in business. I thought I was able to piece it together for a one world award on a combination of CX, QR, and RJ. When I called to book, they said that the QR leg from SIN-DOH is only showing available in economy. Searching on Asia Miles, it shows available in business. I also searched on the BA site and with Qantas, and both of those show the flight available (1 seat left) in business.

The routing I'm looking at is:
6/24 SFO-HKG-SIN (CX)
6/25 SIN-DOH (QR)
- 3 day stay in Doha, then revenue flight DOH-AMM on 6/27 -
6/28 AMM-BKK (RJ)
6/28 BKK-HKG-SFO

I'm not all that familiar with AM, this is my first AM booking. I'm wondering if the agent is wrong, or if trying to escalate or have them check directly with Qatar might show the availability? In searching, I've found that married segments play a lot into availability. For example I can book SFO-HKG-SIN but can not book SFO-HKG. My assumption is that since SIN-DOH is available as a direct flight, I should be able to build it into my OneWorld award. Is CX instead forcing their system to look at it as SFO-DOH and then married segment or routing logic kicks in to remove partner availability?

Just a quick update:

This was happening to me multiple times on other routings. CX and BA sites would show Qatar availability but when I called they agent couldn't see it. They would refresh their system and I checked over the course of a week or two on various routings. I was not able to complete the booking online either, as it would give an error message about the credit card at the final step.

Eventually I was able to get it to book over the phone by referencing the in-process booking I had attempted. They were able to see that transaction and process it over the phone. Only then would the availability show up. But if I called fresh from the start before trying to make an online booking they did not see the availability. Not sure why it was this way, but it ended up working.

Might be a case of an inept agent.

When you make a booking, the availability is locked for a certain time. For normal online bookings, direct with the airline, it might be just 10-20 minutes, though I can imagine, when you try to book QR through the AM site, AM operates as a TA and that period could easily be a couple of hours, just to give the TA the opportunity to complete the whole, including the payment.

The fact, AM could pickup your stranded booking is a hint for that.

And all that time, the award seats are blocked for others trying to book, which explains, why AM could not get your booking done, when starting fresh. Your attempt did block the availability.

Me neither, I learned that from you

Possible, but the same thing happened with multiple agents. I think I called in 3-4 times over a week period, also looking at other routings. They could see economy availability on the route but not business, when the BA site said 1 business available and CX site also showed it. One thing I did notice is that the availability (SIN-DOH) would repeatedly show up, and the next day be gone, then show up again. Every time it showed back up I would call and the phone agent couldn't see it. I didn't want to go through with the online booking because I hadn't secured the first segment to get me to SIN, and wanted to book it all together at the same time.

Could be a bit like my HKG-(CX)DOH-(QR)GRU-(JJ)AEP