Trying to create inventory alert for PER-BKK in December Y and F.
I cant seem to pull up the flights under "award and upgrades" for most dates even though there are flights everyday.
But if search under flight availability, the flights shows up?
Not sure what airline you are referring to, but as likely noted at the top of the results page, many airlines don't return flights that don't have any award inventory in any cabin.
You can still create a Flight Alert for the flight from the results page of the Flight Availability search or via the Create New Flight Alert page. Also you can add a general class, like Y, as an Other Class in the Award search to make the flight show.