I have experienced the same issue. I just updated to iOS 11.2 this past Sunday via iTunes with my phone connected through USB. After the update installed, I attempted taking a picture. I noticed that no matter what I touched to focus on, the image was still blurry. The only way it looks somewhat clear, is if the camera is approximately 6 inches from the surface of the object. Today, I did a little experimenting. I have a wireless headset that has magnetic earbuds to attach to the band. While using the rear camera, holding it to focus on something about 5-10 feet away, I placed the one earbud on the screen side of the phone right over where the lens is on the back. The image then came into focus. While moving the magnet around on the phone screen, just in the lens area, i noticed the lens moves in and out and slightly side to side. My conclusion is that something in this iOS 11.2 software update, is disabling the command of the focus motor function. I am not sure why, other than something in the program is not allowing the camera lens magnet to operate. In other words, it is not physically completing the control circuit to operate lens motion.