Hi Felix, yes the problem in this case is like Pilou says because the shape is a line.

A line does not itself define a single unique plane, and in this case the direction that was picked to project the line out from was the wrong direction for this case and did not intersect the projection of the other shape.

It basically tried to intersect things like this:



That is something that can be fixed up in the future for the Isect command, it should not be too difficult to figure out some special logic to handle the case of a line in a better way.

For now the solution that Pilou gives will work though - draw a little leg on the end of your line and join it to it so that it then the curve has a definite single plane to it and that will then work.

Thanks for reporting this glitch, I have put it on my list to tune up in v3.

- Michael