I was and still am having problems with the fit to wall tool.
I was having trouble with the roof cutting the gable wall, it would not do it until I had the wall on the same level as the roof.
I still am having problems under a stair, some walls will fit to the stair others will not.
Also, you can re-fit to walls, my stair configuration change and I just selected the wall to fit and they did.
Ferger,
using VW2013