Hi, does this issue persist if you don't use Leap Motion?
If you have the same issue with mouse or VR controllers,
then it might be because of distorted body collision.
As you may know, the figures in VaM doesn't have "mesh collision",
but collision created from many invisible geometric objects.
The butt for instance is made of two spheres or balls.
If you will use extreme body morphs, sometimes this collision objects are deformed in a way,
that you can't penetrate the body holes any more.
The balance of those colliders is relatively fragile.
This holds true especially for the male (futa too) figure,
that has never got that much priority in VaM development as the female figure.
There is a complicated plugin to edit those colliders, but more or less I would suggest to drop those distorted custom figures and to redo them all new from the start.
An other approach to your question if this is only with Leap Motion and you don't have this issue with custom figures only:
As you may know, there is a resistance force while inserting something in the body holes.
There is an other force that moves the "user hands". At a certain point the backforce when touching a massive object is so big, that the "user hands" will stop and stays in place.
Maybe this force is less strong while using Leap Motion and the resistance force while inserting is bigger than the force to move the "user hands" or the dildo.
I don't remember much from the very few times when I had tried out Leap Motion,
but I had the impression of the "user hands" movement was not that accurate and forcefull than with normal controllers. It was never a very popular feature in VaM, simply because not many users had Leap Motion,
so it is unfortunately not as elaborated and user-tested as the main features.
But maybe someone else who does actually use LeapMotion will have a much better answer and maybe even a solution.
Long speaking, short answer: I really doubt this issue would be gone after a complete re-installation.