A very problematic area is the coupling between horizontal and vertical regression analysis. Generally speaking, one must create a horizontal regression line first, create regressed elements, couple them together in a complex geometry and then proceed with vertical regression. The problem is that if one takes away the regressed elements from horizontal regression and replaces them with geometric elements, this coupling is lost and as a result for a given horizontal geometry, the vertical regression line which is produced is faulty. In the case below, I had 84 survey points with XYZ coordinates which form the regression line and I wanted to create a vertical regression line to compare it with a geometry which was produced from 3D rails. Instead of getting a vertical regression line from survey points with a curvature following the leight of survey points, I got an almost straight vertical regression line with only 6 points.

Please adress it as soon as possible, as this is a very vexing problem with not so easy workarounds.