I cannot access the Radeon Additional Settings and I get a message saying there are no addtional settings to adjust. However, I recently installed a new copy of Windows 10 and my highest resolution is set to 1600x1200 but I have a 1920x1080 monitor. I needed to access the Radeon additional settings to uncheck that box that lets me unlock higher resolutions. After installing the new Crimson edition I cannot access the additional settings which I could in the earlier versions.
GPU: R9 270
Windows 10 x64
Radeon version 16.12.2 crimson edition
It's a known issue. Keep using the previous drivers until a fix is issued.