I’ve bought the full shadowlands i got everything but not the wraithchill trasmog for weapons i lookd on differend chars with differend weapons but nothing there , i rebooted the game and launcher too but after a couple hours logging back in still nothing
Have you tried switching realms and then back to your main one? As that can force it to appear in the Weapon Enchantment section of transmogrification. Also try a different weapon, as those that already have effects on them can’t always use the Wraithchill Illusion.
Just did that still nothing when i look in my collections i cant find it there too 
i have the same issue, did u find any solution yet?