I recently rooted my Galaxy S5 (running 6.0.1) and it went fine. SuperSU is working, Busy box is installed, and every app I've downloaded since rooting has been granted SuperSU access easily. However, the apps I installed before rooting cannot detect the root. I usually get a message along the lines of "this feature requires root access" or "root not found." There is no prompt to grant the apps root access. I've tried uninstalling and reinstalling the apps and rebooting my phone several times and nothing has helped.