Is it a bug ? FIDE rules say :
"The game is drawn when a position has arisen in which neither player can checkmate the opponent’s king with any series of legal moves. The game is said to end in a ‘dead position’. This immediately ends the game..."
K+N vs K+N can end in checkmate through a series of legal moves, if one side is determined to lose, so I don't see anything in the rules that suggests it should be an automatic draw
I played a game which ended in a knight versus knight endgame that was not an automatic draw. I had to jump around like a maniac in the zeitnot. Please fix this bug!