curve deformed by curve . . . no front/back?

Hi, does anybody can say if this is OK?
When I tried to deform curve object by curve can’t get front / back surface on it.
(when curve object is 2D result is mess, when I switch curve to 3D option front / back surface disappear.

Do I something in a wrong way or is this how it suppose work (or bug?)?
Thanks for help.

The back/front fill is only available for 2D curves

OK, but 2D gives me this strange result.

OK, I solved it.

I have no clue what is going on, I solved it when I rotated deformation curve 90° in Z axis (than I just rotated model in edit mode to deform model from right sides).

But why this rotations I asked my self? So I changed back Z axis of deformation curve back to zero and rotated model in edit mode back. And It works too. Than I save it and open again and model was corrupted as before. OK this can be some preview problem. It’s terrible to see things that are not exist, but anyway . . .

Can someone explain me why it works with rotated Z axis in 90°?

Please check this .blend file,
because it’s not a first time that I had this problem.
And I really want to know what’s going on.

Layer 01 - corrupted
Layer 02 - is OK

Thank you very much.


curve-2D???.blend (301 KB)