Offset curve goes nuts?

Soo, when i offset a curve ( 16 points degree 3 ) it goes nuts? why ?

You may have “Cap” on? This, in combination with the fact that the offset is too far to cope properly with the higher curvature on the ends of the curve, may give this nuts behavior.
Could you share the 3dm file with this curve?

Check what type of corners do you use. I found that sometime changing the corners to round the offset works better.
Is this crv 2d or 3d?