I was trying to book a TPE-SIN/SIN-KUL/KUL-TPE trip in Y yesterday on the App. During the selection process, the SIN-KUL had 0 miles only for some days. However, when it priced, it added the 12,500 miles no matter what. So, instead of 45,000, it priced out to 57,500.
The funny thing is at the price breakdown, it showed 12,500 crossed out and replaced by 57,500
Yes, it makes no sense that if your flights are all in Y. This means it won't work anymore.