So I'm starting to ponder, how on earth has this #64 puzzle not been solved yet?

I have personally solo checked about 35% of the keyspace in the past 15.5 days, with a comparatively slow speed of ~150 MKey/s.

I've seen this #64 puzzle has been the main target for about a year?  And there are several pools checking BKey/s , many other BitCrackers who are getting >700 MKey/s, etc.

I'm starting to get skeptical that the 16jY7qLJnxb7CHZyqBP8qca9d51gAjyXQN  address is even in the 8000000000000000...ffffffffffffffff keyspace at all.