My system is a ATIV Book 8, model NP880Z5E-X01UB. Also Intel HD 4000 and Radeon 8700M GPUs.
I recently updated W10 to anniversary edition and ran into this issue yet again. I have no idea how I was able to resolve it last time. I attempted to uninstall, and reinstall all drivers from Samsung over again, in various orders, running the Win10 Brightness Control Patch each time provided by Samsung Update, but in each case, never yielded results. I should also note that I've also disabled adaptive brightness in display options and also my power options plan. This was required the first time I got this working so I made sure those settings were changed back after the update reverted them.
After some more intense googling.. I finally found a solution that worked for me.
Modify the following registry key(s):
Change f000 to f008
There are other "control sets" other than the CurrentControlSet. I wound up changing them all to f008 prior to a reboot. Though I suspect the CurrentControlSet is all you will need.
As always, careful when modifying the registry.