Advice for muscle gain?

Hey everyone, over the past year I've gone up 15kg and now weigh 77kg (male, standing at 6ft). This is great, but the problem is I eat about 3000 calories and go to the gym 4+ days a week (push/pull/legs split) yet I have barely gained any muscle at all. I've gone from 8% body fat to 18%, gaining maybe a kg of muscle, despite all of the time, money and effort I've put into my training and diet. Does anyone have advice to help me finally start building muscle? I progressively overload and eat over 150g of protein a day and eat very healthily so I'm at a loss. Thanks