Rigidbody addForce when colliding with 2 mesh colliders

I have a character with a rigidbody and a box collider, and I am using mesh colliders along different chunks of ground to walk on. The character jumps with rigidbody.AddForce(Vector3.up * jumpForce). This works fine when the character is on a single chunk (middle or corner), but if he stands at a point where two sections meet (where he collides with both), his jump height gets cut down (about 1/4 or less what it should be). Does anyone know what might be causing this issue?