It works well on my computer. (I use Rhino 7.11.) Maybe you do not know how to use it? The SoftTransform command has no effect on Rhino objects - its sole purpose is editing/changing Rhino sub-objects (vertices, edges, faces, and control points). Read my post about the SoftTransform command: Rhino 8 Development - #79 by andrew.nowicki
SoftTransform documentation is here: