Hardest chess problem. Stockfish 12 can’t solve it.

It's not seeing it for me. I use the Chess.com analysis though, don't have any other way.

I don't get this, how does my analysis not see it, if the win is only 13 moves deep, why does it miss it at depth 45+? I guess it doesn't even consider the moves. 

Anyways, cool puzzle find.

SF is not a simple brute force machine. That is reaches 45 only tells you there is at least one variant calculated to that depth. Even I can do that when I am in good shape. I have seen SF miss checkmates in just 4 moves though it will probably find them given an hour. Note that you share this engine with loads of other users on chess.com and engine time gets distributed over thousands of simultaneous analysis jobs. Private engines may do a lot better.

Wow, zugswang with a queen and bishop on the board and discovered checkmate threats.