Box incorrect collision with convex

[wenerme]

The brown part is the static water,build by convex, in the end, the box was flying out of the brown part,but the circle is fine.

        let water = this.water = new p2.Body({
            type: p2.Body.STATIC,
        });
        water.label = BodyLabels.water;
        waters.forEach(w => {
            w.forEach(a => {
                let convex = new p2.Convex({
                    vertices: Matter.Vertices.clockwiseSort(a).map(v => [v.x, v.y]),
                    collisionGroup: Collisions.water,
                    collisionMask: Collisions.blockMask,
                });
                water.addShape(convex);
            })
        });
        world.addBody(water);

The box is very simple

            let body = new p2.Body({
                mass: 1,
                position: [350, 480],
            });
            body.addShape(new p2.Box({
                width: 72,
                height: 36,
                collisionGroup: Collisions.rock,
                collisionMask: Collisions.blockMask,
            }))
            world.addBody(body)

// MyWorld extends p2.World
let world = new MyWorld({
            gravity: [0, 0],
});
world.solver.iterations = 50

But I do use pixel unit, dose this will cause the problem ? because kms is not very friendly.