What happend to Stockfish8 (B+N mate)

I just played 'from position' against Stockfish8 with a black king against king+bishop+knight for Stockfish. Whatsoever it wasn't able to checkmate me and eventually lost the bishop. Now, wasn't Stockfish8 supposed to be incredibly good? Or what happened?
Here is the game: lichess.org/eXRDYfuz/black

Without the Nalimov tables, this endgame is too hard for Stockfish8.

AI level 8 is handicapped and isn't playing at full strength:
github.com/niklasf/fishnet/commit/e4bfbf8fce99137c1d0c13918ba208eed3e0447b

Stockfish 9 at full strength easily wins this endgame.

Thank you, but if so, why isn't there a way of playing against an unhandicaped engine?

Why not just analyze the game using the B+N tablebases? They provide far more information than SF ever could.