I have the same problem. Asus with Radeon 6xxx series. The screen ignore the Windows 10 brightness settings. Very very annoing...
I also have the same problem. After update to Windows 10 I cannot change brightness. Brightness slider/clicks on battery icon doesn't have any effect. 15.7.1, tried update drivers.
Moreover after sleep mode or while switched to battery power brightness is reduced and to increase it back I need to reboot computer.
Laptop Asus n56dp, radeon 77xx series
I have Asus N56DP too and the graphic card is AMD 7730M but by the last update the brightness doesn't change with f5 and f6 and also with the battery power option.
But there is a way that you can change your brightness,here it is:
open Catalyst Control Center--->go to 'My built-in Displays'--->go to 'Display color(Built-in display)--->there you can change the brightness and press apply botton
Fixed it by updating my driver. I believe it was a driver that had something to do with either AMD or with the visuals of the computer (forgot exactly what they called it)...