Had no problem selecting a meal for my upcoming BKK - SYD flight in F in March (booked via UA miles). I went with the lamb chops though like others it shows as "vegetarian hindu" in the seat selection tab.
I assume it's a display error or just the fact they haven't coded in all the various F meal possibilities into the seat selection screen (I don't know what a hindu meal is but I'm 100% certain lamb chops with mashed potatoes and bacon is not a vegetarian hindu meal).
Still no F award space on the NRT - BKK a380 flight that precedes it a couple days earlier though