I'll try and break it down for the people who believe he was onside,
1) the ball was played to Rashford.
2) Akanji plays him offside.
3)Rashford runs with the ball within playing distance
4) Rashfords team mate shouts "Leave it"
5) he leaves it.
1) & 2) he's active when the ball is played to him and impacts on Akanjis decision making : Interfering with play.
3) He runs with the ball in playing distance because of this he impacts on the decision making of Ederson and the defenders: Interfering with play.
4) & 5) He gets the Instruction, Leave it, he is then part of the move, Active!! : Interfering with play.
The officials the pundits the Rags and any one who thinks it's not offside need to find another hobby and don't give me this Grey area shit It's a really bad decision.