On the main fader in studio one, select the digital return (2track l+r) in the black box at the top of the fader. Then in the main mix in UC Surface, scroll all the way to the right to see the fader for the 2 track, and make sure it is at unity (0db), then use the main fader for overall volume.
Also, how are you connecting the RM and the CS? Direct ethernet, or via a router?