Hello!
I think there is a bug with Crafty Shield. Veekun's entry for Crafty Shield says, "Unlike other blocking moves, this move may be used consecutively without its chance of success falling," but Crafty Shield still fails when used consecutively on Showdown. I was able to use the move consecutively 10 times in Alpha Sapphire. I tested it with a Klefki and Smeargle on Showdown and it failed when used consecutively: http://replay.pokemonshowdown.com/ou-205870719.
I think there is a bug with Crafty Shield. Veekun's entry for Crafty Shield says, "Unlike other blocking moves, this move may be used consecutively without its chance of success falling," but Crafty Shield still fails when used consecutively on Showdown. I was able to use the move consecutively 10 times in Alpha Sapphire. I tested it with a Klefki and Smeargle on Showdown and it failed when used consecutively: http://replay.pokemonshowdown.com/ou-205870719.