How do you fix this.

[JVMerlino]

Yes, you guessed it, I found a bug.
Or should I say a dumb logic mistake.

Beware of other subtle logic mistakes. It took me over two years before I realized there was a bug in Myrddin that caused it to fail to check if a move that would cause a 50-move draw would ALSO cause checkmate.

[bob]

And as ChrisW mentioned. you don't need 3 repetitions, you only need 2. If the engine repeats the second time and can only reach a draw score, what would it do differently before reaching the 3rd repletion as opposed to doing the same thing before the second. MUCH more effective.