This is my second m8 I recently updated to 4.4.4 with at&t now my camera refuses to focus I can see well on the camera when the object is about an inch from the camera but, anything further and the camera gets unfocused.
Check to make sure the camera lens "protective" film isn't scratched. If it is, use a cotton swab and rubbing alcohol to remove the film (which is stupidly a scratch magnet).