Why Is My External Monitor Is Not Working?
If you have a 4k or 5k monitor attached to your Mac and notice Luna Display isn't running properly, try removing the monitor to see if there is any difference.
The Luna Display dongle cannot be plugged into the Mac on the same side as a 4k or 5k display, and we suggest plugging Luna into a port on the opposite side of the display.
If a 13" MacBook Pro (with USB-C ports) is in use:
Plug in Luna Display to the MacBook Pro first, with both apps running, and then plug-in the 4k or 5k monitor afterward.
For example, orient your monitor on the left side port and Luna on the right side port.