Why did Joao Felix's goal against Granada get ruled out?

Barça came close to coming from 2-0 down to take all three points but, in the end, had to settle for a draw against Granada that many would have signed for with ten minutes to go.

However, Joao Felix did put the ball in the net, but it did not make it onto the scoreboard. 

The reason? Soto Grado disallowed it for offside against Ferran Torres, who although he tried to attack the ball did not touch it, and the VAR ratified his decision without the referee going to check it.