LG 27UD88-W --> NO SIGNAL (Macbook Pro 2018) USB-C

Hello danields21,

Thank you for using Apple Support Communities!

I understand from your post that you are not receiving a signal from an external monitor you are using with your Mac. Make sure your Mac meets all the requirements and you have the correct adapter as described in the article below:

Use external monitors with your Mac - Apple Support

Best Regards.

The name USB-C refers ONLY to the connectors, It does NOT uniquely identify the cable. Many many different cable have at least one USB-C connector, and they all have different capabilities.

The cable Apple ships in the box for charging has only charging and USB-2 (think keyboards) capabilities. It can not POSSIBLY run a display of any description.

That display will give your its best performance with a third-party adapter to DisplayPort. Get one rated for "4K" for best results.

It may be able to connect with an HDMI adapter, but there is a lot of "black magic" in getting displays over 1920 by 1080 to work using HDMI. All the cables and adapters have to be just right, and then it sometimes still refuses to give you acceptable refresh rates anyway.

It is possible the USB-C to USB-C included with the display (if so equipped) might run the display. The owner's manual reminds you that you must use the supplied display Power Adapter, the display can not be powered from the computer.