From the image, it looks like a joint parameters issue around the thigh/knee.  I've got the same FireDancer outfit.  It is one that I know in the past has given me problems with the original Wardrobe Wizard, so I tested the conversion with version 2 as well. 

It definitely works much better with the new WW2 release.  It appeared to work fairly well for me when I chose the "Loose Skirt" option for both the belt and skirt.    Attached is a comparison picture. 

On the left, V3 with the original FireDancer outfit
In the middle, V4.0 with the original WW conversion.  No joint parameter adjustments.  (the hair is from the new WW2 conversion, I didn't take the time to convert that under WW1).
On the right, V4.0 with the new WW2 conversion.  No joint parameter adjustments.

Note that my conversion from the original WW had much the same problem.  The only problem I seem to have with the new conversion is at the base of the skirt.  And I think this could be taken care of with a bit of joint parameter tweaking.