Sweep 1 with Helix flipping out

Ok I figure I am doing something very small and wrong as I cannot get a curve to sweep on 1 rail without flipping its alignment direction. Any ideas as to why this would not align and flip like this?

Try it in the Right or Front viewports so the profile doesn’t pass through a vertical orientation.

Or you can stand up the helix so you can run the Sweep in the Top viewport.

Usually the best way to control alignment of the shape as it sweeps is to use Sweep2.
HelixSweep2.3dm (194.3 KB)