Good job blizzard. Achiv for Meta, bugged and only horde players see this. Really god job. I have advice. Try start use brain!
BTW. Player which play only one character on alliance or Horde cant complete meta achivment… Its not possible.
Its not really a bug, there is couple of faction restricted achievements in this Meta achievement, so you actually need to have both faction characters.
Its highly confusing also, because if you click on the achievement in the Meta Achievement, opposite faction’s achievement is not shown at all leaving player confusing, forcing them to use outside sources to find info.