After you apply zxz0O0's fix you should have working dual recovery, you will know if it's working since you'll see a purple notification light followed by 2 small vibrations. Spam the volume down key when you feel the vibrations and you'll enter the recovery. There go to Mount and check the System box, then go Reboot -> Reboot to System. Once the phone booted up open SuperSU and uncheck the Mount Namespace Separation checkbox and reboot your phone again. I also ran
this file taken from
here, but that's because I didn't get working recovery from the first time, not sure if it's necessary. That's basically all I did.