Sure, examples exist. E.g. Game 6 of Carlsen-Caruana, World Chess Championship 2018:
[FEN "5k2/8/5pK1/3B1P1P/3n4/8/3b4/8 w - - 6 67"]
Kg6? loses, but no human would have found the refutation.
As for games where the exact losing move cannot be found even by the best current engines - I spoke to a correspondence chess expert recently, and I'm confident they ...