I can't see the number of the problem until I've 'solved' it. White has a K+Q and Black has a K+R. The pieces are in the lower right hand corner of the board. W- Ke2 Qg6 B- Kh3 Rh1.
I've fixed this bug. Now if the engine play an inferior line and let you mate in less then the expected numer of move the solution is correctly evaluated.