After DAYS of troubleshooting (which included a ton of restarts, deleting that .cs file from preferences & even eventually completely wiping out my iMac & spending 14 hours (awake) reinstalling Yosemite, all of my programs & plugins... None of that worked. Spent an additional 4 hours yesterday to arrive at the conclusion of what DOES work... Or at least worked for me:
1. Update your MCU Pro & XT Pro control surfaces to 4.0.3 (still no update for the C4 Pro)
2. Delete the control surfaces on LXP within the control surface setup
3. Quit LXP
4. Delete that .cs file in the hidden preference folder.
5. Turn off MCU & XT.
6. Restart Mac.
7. UNPLUG all midi cables & usb from MCU & XT (including those plugged into each other).
8. Launch LXP & open Control Surface set up.
9. While holding select buttons of faders 1 & 2 on each unit, turn on MCU & XT then select Logic by pressing vpots on either channels 7 & 8.
10. Plug MCU's USB into Mac (or your USB hub) then scan for new device.
11. Once the MCU is read/confirmed, plug the midi for the XT into & out of the MCU then scan for that device.
Follow step 11. for each XT Pro & you should be back up & running. I hope this helps.
Best,
88-Keys of Keys Open Doors LLC / Very Good Beats, Inc.