Hi Olga - those stretched shapes happen because of slanting connections in between the rails.

For example here is a cross-section taken from the center part of the MoI sweep:




Notice how that section is slanted between the 2 rails? That makes the section scaled up to be bigger, because a slanted section between 2 rails is longer than a section that is closer to perpendicular between 2 rails.

It looks like this is being caused by differences in control point spacing between the rails, which MoI's sweeper is currently sensitive to. But I am planning on doing some work to fix this up for v2 though, it is a fair amount of work so it won't be for the very next beta release but I plan to get it in before the v2 final release.

- Michael