When I connect my MacBook Pro to my LG 4k display, I get power and sound but no display

Hi MaxNipper,

We appreciate you reaching out to us.

We’d like to gather additional details that may help us be in a better position to assist you.

Did you use the same steps in the article below to connect the display?

Use an external display with your MacBook Pro - Apple Support

If yes, please try the steps below to troubleshoot the issue.

"If your external display is dark, make sure that its brightness hasn't been turned down.

• If your keyboard and external display are made by Apple, you can use the Brightness Up key  on the keyboard to increase brightness. Or choose Apple menu  > System Settings (or System Preferences), then click Displays and use the brightness control there.
• If your external display is not made by Apple, you might need to use its built-in controls and menu system to adjust brightness. If you can't do that and your display is dark, the display might not have power, or it might be malfunctioning."

You can use the article below as a reference.

If your external display is dark or low resolution - Apple Support

If the issue continues, please check if the issue happens while on safe mode. 

Safe mode does a basic check of your startup disk, similar to using First Aid in Disk Utility.

Performing this step may help resolve the issue, or further isolate the issue.

Below is an article to help guide you through the process.

How to use safe mode on your Mac - Apple Support

Take care!