When working with very fine data you had to keep a minimum distance between two points of 0.01 (value range 0-100) or 0.0255 (value range 0-255). Under certain circumstances this may not be fine enough, as a result the minimum distance has been reduced to 0.001 or 0.00255. So, if you set a point at a distance of at least 0.0011 or 0.00256 it will appear at the desired spot. If the distance is smaller, you will only shift the next available point on the corresponding axis.