Macbook Pro 2019 Bootcamp external display switches to 30hz when laptop lid is closed I am having the most frustrating problem. I have a 2019 Macbook Pro (AMD 5500M) running Windows 10 / Bootcamp. I have a 4k UHD external display which will not display above 30hz. I thought it could be the cable, but somehow discovered that when the laptop lid is open, both displays will run at 60hz! 
I close the lid, and the display switches back down to 29hz. There is no way to change this. 

This problem ONLY occurs in Windows 10 / Bootcamp. This does not happen on Mac. 

Here are the screenshots for the monitor settings

https://imgur.com/a/QyOVoRS



Other things I have tried

Just disabling the monitor in the display settings (use only thing monitor). That also changes the display to 30hz. 

I have looked around the power settings thinking there is some strange video switching, but i can't find it. 

Any help would be VERY much appreciated. 

Thanks!
As it turns out, this is an issue with the 2019 Macbook Pro and Bootcamp/AMD drivers. The solution is easy. Switch the resolution to something other than the default, and watch as the refresh rate magically increases to 60hz. Then just set the resolution back to the default setting and the refresh rate will still be at 60.