Ninian Linesman/ Whitts offside

Why one Earth did he give Whitts offside up by the edge of the box in the second half? He skilled and passed his way through the defence, shifted past the last defender and picked it up on the other side and was offside?!

I thought he gave it against Mason as when Whitts dribbled through he bumped into Mason therefore interfering with play
Allegedly

I thought he gave it against Mason as when Whitts dribbled through he bumped into Mason therefore interfering with play
Allegedly

yes mason went towards ball which constatutes offside as he was active! he changed his mind when saw whitts going for ball
but to late linesman was correct