I confirm there are not any, I just modified my code to return after finding one solution, it passes the fixed tests and rarely the random ones too (I had to spam "Attempt" a hundred times).
EDIT: my code prechecks that the initial number of filled squares is higher than 17 (otherwise we are sure there are multiple solutions), maybe that's the issue. There should be cases with more than 17 squares filled and multiple solutions.

They call these types of problems "code golf", because getting your code to as few characters as possible is similar to getting strokes off your golf game. And after this kata I discovered I find it a very painful experience.

Why golf?

This threw some kind of error but passed anyway

I was stuck at 138 and couldn't get it down lower. My maths was as concise as it needed to be. I came back after a while and quickly got it down to 128. 138 -> 128, so you might say the "3" became "2".

Same here. I just get down to exactly 138. Have you got progress in the past few months?

I swear to never start another golf challenge

this is hilarious

There should be an "At Least You're Honest" rating

Odd, I might be mistaken

but there are fixed tests with multiple solutions... :o => ?

Madman!

congrats! ;)

nope, no way to enforce the hard way. ;)