017 MacBook Retina Not Connecting to LG UltraFine 5K Display
I was having trouble connecting my 12-inch 2017 MacBook Retina to an LG UltraFine 5K Display, and I saw this posting that had the same problem:
https://discussions.apple.com/thread/251154985
There were others that appeared to have the same problem, but I didn't see a solution. I had connected the USB-C port to the monitor using the Thunderbolt cable that came with the monitor, but that only provided power to the MacBook but did not cause the display to work. After nearly returning the monitor, I decided to try using the USB-C cable in the box that was marked as being needed for an iPad Pro. I connected the USB-C port on the computer to the Thunderbolt port on the monitor, and this caused the display to work and the monitor also powered the MacBook.
I thought I'd share my experience so hopefully anyone else who ran into the same problem might find a solution.