A quick database query shows this is the first puzzle in LMI tests not to be submitted by anyone.

I was on my way to submitting it, and made a counting mistake and thought the solution was wrong. Only one to submit a puzzle correctly would've been quite a nice stat. Ah well..

Anyway, I don't think this is due to the puzzle being extremely hard or something, while it was definitely one of the tough ones, I think the main reason is the high percentage of easy puzzles in there that people would attempt before it. Whatever be the case I really enjoyed working through it and the rest of the puzzles on the set.