If I look at the lens, while the focus is stuck, the lens, naturally, also don't move as they move when the focus is not stuck.
What could this be? My bet would be an issue with camera, but I'd like to exclude any possible known issue, before I RMA it. I still have few months of warranty. Normally I would be doing the factory reset, but I was kinda waiting for the 4.3 or 4.4.2 update, and fresh flash.
I'm running stock 4.1.2 (still the latest official for me), and it is rooted, and triangled away. Everything else is stock. I use stock camera app. Also I don't seem to have any other problems. When it does focus, the camera produces sharp photos. SO no problems there either.
PS The lens are clean and undamaged, as is the whole phone.