Someone mentioned on flyertalk that the SFO CX lounge only accepts the first 10 non CX pax OWE to arrive at the lounge due to space limits and that QF provides a list of CL pax. So once the 10 non CX pax enter the lounge, they don't let anyone else in unless they are on the CL list or are CX pax.
I've had similar issues with the BA lounge at ORD when flying QR and RJ. Both QR and RJ use the AF lounge at ORD. The time I was flying on RJ, I attempted to enter the BA lounge as OWE on a oneworld flight. Even though signage said the lounge was open until after the RJ flight boarded, they said they had just called the BA flight, so were closing.
The next time I was there, I was flying QR and went to the BA lounge. They tried to refuse entry even though I showed that I was on a oneworld flight with oneworld status (and in J). The lounge agent tried to send me off to the AF lounge that QR contracted with, until I said that I'd been in the AF lounge before and the BA lounge was likely better then the other lounge. Then they realized that my flight boarded before most of the BA pax would arrive and let me in.