Referee Juan Martinez Munuera of the Copa del Rey semi-final match between "Barcelona" and "Atletico Madrid" explained in his post-match report the reason why the VAR system could not detect the offside.
Idman.Biz reports that the game ended with a score of 4:0 in favor of "Atletico".
"During the analysis, it became clear that the system had problems modeling the players at the skeletal level due to the high density of players. After attempting to recalibrate the model and discovering that it was not possible to do so according to the established procedure, the VAR team began drawing the offside lines manually to make the final and correct decision," Munuera's report said.
The referee spent more than six minutes determining that the goal scored by Barcelona defender Pau Cubarsi in the 52nd minute of the second half was offside.