Are you sure you're on a "rooted" ROM? Sounds to me like you have root and unroot confused. Did you buy the Tab new? Is it how it came from the store? If so you are not rooted. Rooting is what one does in order to be able to flash custom ROMs.
if i flash the build of 14th then i stuck on samsung boot logo. firmware was stock rooted deodexed 4.4.2. i have tryed it twice but always stuck on boot logo.
I was sameway, so I just downloaded the update from "sammobile" installed it and used...
find an aokp jb ROM in dev section, do full wipe, flash new ROM w/correct gapps. enjoy.
you're already running jb, but it's a stock/rooted official jb ROM ;>
you're already rooted, that won't change unless you flash a stock jb firmware via O...