Hi possum, could you please post the 3DM model file with those curves in it so I can test with them over here?

That probably looks like a bug that will need to be fixed - it could be possibly something like a limit to how many points are used in the deformed result, that probably requires a pretty big number of points to reconstruct something like that and some limits may need to be raised.

Are you able to get a proper result when using a helix with fewer turns in it?

- Michael