Did you flash a SU file when you flashed the ROM? Both dr87's and utesred's guides say to flash a SU file with the ROM. From utesred's guide
Within TWRP, you need to do a standard wipe. After that, flash the ROM file first, and then the SU file after. DO NOT reboot your phone in between the files. If you do, you'll have just flashed the rom you had two hours ago when you began, and still not have SU. Once you do have them both flashed, reboot your phone and you're done.
I would like to hear what you did as I am going to be rooting this phone soon, but I'm still on the shipping JB ROM.
Samsung Rant > LG Optimus V > HTC Sensation 4G > LG G2 D801