this is not a bug. it's how is supposed to work. When you heal blind and chaos the ninjas get back their standard attacks (why should they lose it if are healed? Only immobile makes them lose them regardless the fact they were healed) and is not true that barrier ninja mystery becomes prompt. It becomes prompt if the mystery is used after the standard attack move of the ninja passed, otherwise with blind you would not only negate the standard attack but also the mystery, would be a bit too much, don't you think? There's chaos to prevent mystery usage too.