Actually, it's possible that all WE nobles on foot have been discontinued, or in other words, made mail-order only. It shouldn't be a problem for GW stores, but there is a possibility that independent retailers cannot order them normally.

Wood elf nobles are not the only ones, 40k has many examples of models that belong to the current range, but cannot be ordered by retailers. Necron Tomb Spyders and Ork Big gunz to name but a few.