There was an issue with users losing root access after either updating to MIUI 1.9.9 or clean installing it. This issue affected me personally and was rather irritating. Especially since last night was my first experience with MIUI and I was scared when Titanium back told me I had no ROOT, to check if busybox was installed and my ROM was ROOTED. I did what any good flasher would do, I rebooted the device. still, no root. Then I checked to see if I still had ClockworkMOD recovery. Yup, still there. Everything seemed to be normal and functional, I just didn’t have root any longer. It took a while, but I found the solution.
If you are in the same boat as I was last night, have no fear. This is probably the stupidest and easiest fix you will ever experience in your life. Unlock your device and go to “Tools”. Then select “Superuser” Â and then hit menu and select settings. You will find a very nifty little toggle button named “ROOT permissions”, turn it on. You may need to reboot the phone or make sure to complete stop any program that you were trying to run that needs root access before it will work. I just rebooted to save me some headaches. Here is a super quick video of how to do it if you are more of a visual learner. Gotta love Screen Cast for making these short videos possible.
Thanks MIUI.us team for the helpful info.