Does BitCrack always find keys or can it miss?

I have searched the whole of the puzzle 64 range and not been able to find the key 16jY7qLJnxb7CHZyqBP8qca9d51gAjyXQN

0x0000000000000000000000000000000000000000000000008000000000000000
0x000000000000000000000000000000000000000000000000ffffffffffffffff

https://privatekeys.pw/puzzles/bitcoin-puzzle-tx