Well I am trying to fly NRT-SIN around 20 Dec but found out that M fares (and most other cheapy classes) are zeroed out on Sabre for JL711. It seems that they have simply chosen to block out all but full Y/B/H fares for all of mid-late December until January 5. Is this an annual habit for JL? Why block out only the evening flight and not the morning/noon flights on the same route?

I am assuming that closer to the dates the M fares will be released...?