Did you do an upgrade over top of Win 7 or a fresh install? I did a fresh install and LR6 is working fine for me.
If you are using a wide gamut monitor
- Start with getting the latest Win 10 driver for your ATI card.
- If that doesn't work: Since you are adjusting things manually either with monitor controls or with Windows "Color Calibration" (and maybe in the ATI Catalyst software?) I'd be tempted to first put all of that stuff back to their defaults then see if the issue is still there.
- If that doesn't work: I'd uninstall/reinstall LR.
Also, if you have a wide gamut monitor don't use your desktop image as a guide to adjust colors or contrast under Windows "Color Calibration". With Windows 7 you could use an aRGB image for the desktop image and it will display correctly on a wide gamut monitor. With Win 8 they took away the ability to use an aRGB image unless you did some geeky things as a workaround. With Windows 10 they seemed to have even taken away the ability to do a workaround. As a result Win 10 forces you to always use an untagged sRGB image for the desktop, so the desktop image displays overly saturated and really contrasty (even the ones that come with Windows 10).
Soooo ... if you adjust things manually on a wide gamut monitor base you adjustments on what you see displayed in a proper color managed program, not what you see as the desktop image.
Also, instead of making manual adjustments maybe see if you can borrow a calibration device/software from someone or see if a pro camera shop will allow you to rent one for the weekend. If you do a proper calibration just make sure you set everything in Windows color calibration, the graphics card software and the monitor settings back to their defaults first.
For Win 10 you access "Color calibration" by:
- Right clicking on the desktop
- Pick "Display Settings"
- If you have a dual monitor setup pick the display you want to adjust
- At the bottom of the screen pick "Advanced display settings"
- Under "Related Settings" near the bottom of the screen pick "Colour calibration"
- Follow the instructions