To use Delta Skymiles on booking award seats for China Airlines, I was watching over the availability of business class (85k / JFK-TPE) for some weeks.
The date I want to fly on was just enough for more than 4 people, but all of the sudden by yesterday it shows "Sold out."
I also searched for other dates for same Mondays, but it shows "Sold out" as well, which I saw plenty of empty seats in the past a few weeks.
Then, I also went into China Airlines website to see how many revenue business seats are available on the same airplane, but only 10 out of 40 were reserved.
What's even more interesting is, I also searched for other routes (SFO-TPE), but plenty of award seats are available and even the revenue business class tickets were reserved by 13 out of 40.

It comes to my guess that JFK-TPE is pretty popular route so that China Airlines is waiting for the revenue purchasers buy the tickets first and then release the award seats later on?
I hope that's the case, but don't know what to expect. I kind of heard Delta updates/rearranges the seating/pricing every Saturday, which I really hope the only reason of this change.
Please give me some tips or suggestions about what to expect or do at this point. I really need to fly on this plane for the exact date. Thanks!