If your MX Vertical mouse loses connection after switching devices while connected using the Unifying receiver, do the following:

1. Make sure MX Vertical is turned on and the charging cable is unplugged.
2. Using the Easy-Switch button on the bottom of the mouse, select the channel you want to pair to. If you did not pair to the channel previously, the LED should blink rapidly.
3. Plug the Unifying receiver into a working port. The channel LED will stop blinking and glow steadily. 
   NOTE: A USB-A port required.