Side note for when you get this working - I found it much more enjoyable and educational to mixdown back thru the x32 rather than inside the Reaper software myself.
Great for playing around with effects and DSP on the board, but it can become quite a distraction and very time consuming.
Don't be surprised if you find yourself up all night mixing down just one song. I have recordings from last May I have never gotten around to mixing down because I recorded a bunch of bands over a very short time period and have never found the time to play with the tracks.