Puzzle #E5tEK is incorrect

Hello everyone, in this puzzle lichess.org/training/E5tEK system accepts only one solution out of two existing: after 40... Bf2 41. Bb5+ I made 41... Kf7, which is winning (engine says that there's a forced checkmate), but it was "incorrect" and I lost points. Of course, 41... Kf8 also winning, but not accepting the correct move is outrageous!

It takes a while for the engine to see that it's winning. I've reported the puzzle using the dialog that shows up when you analyze a position in the puzzle and it sees multiple winning moves.

Apparently Kf8 is the slightly faster mate, not that the difference between #-16 and #-19 matters.