How accurate is the online search engine vs the call centers?

I'm on waiting list for YYZ - TPE - SIN and will need to get on these exact flights (so to spend 25000 more miles is small amount to get a peace of mind). From my online searching, it says YYZ - TPE - SIN is on waitlist, but if I book them separately, as YYZ - TPE, TPE - SIN, the waitlist pop up does not appear, so I'm assuming this is available?

SIN Call center claiming they cannot see the availability, and that they have different availability for online and their system. Not sure if the call center is right and I should cancel my waitlist to try book the un-married segments, at a cost of 25000 miles more, which I'd need to transfer in.