From what I can see in the photo is that the bolt heads holding on the der. hanger are not flush and as mentioned, harder than the lower contact surface of the dropout creating an uneven surface. This looks to me like a design flaw. I would contact Merida with your photos and see what they say. If no love from Merida I would try filing down the heads of the bolts (removed from the bike) until flush or slightly beneath the dropout surface.