Hmm, I iuet switched back to the stock LG keyboard to test this out. 'Ur' shows up just fine and isn't being replaced by 'it' or anything else. That's while using gestures to type. If I type by tapping, it doesn't auto-correct at all. The LG keyboard is built on top of SwiftKey technology but unfortunately doesn't behave exactly like SwiftKey (which is why I use SwiftKey).
Wish I could have been more helpful, but that's as much as I can do unless I know exactly which keyboard is exhihiting this behavior.