I frequent the DAC-HKG route. Sometimes I notice that ITA (or other sites like Kayak) don't show the lowest Restricted Economy prices on their searches. I thought at least ITA search would be comprehensive.
For example, for a upcoming travel next Fri, ITA shows no availability in Y. But the CX site & KA site both show Supersaver ("S") fares available at $7xx.
In other times, the fare shown in ITA/Kayak are too excessive (like $12xx) while, on the airline website, it is still $7xx.