advanced rendering for AutoCAD
Hi show us an example, and attach the drawing, some basic things, check your units, put the model close to the wcs origin.
Hard to say without seeing a picture (and perhaps even a model.) If the shadows resolve when you let the rendering cook for a while this is likely normal behavior (the shadows are temporary artifacts caused by sky hemisphere lighting.) If the shadows do not resolve but seem sharp and permanent then something is probably going wrong.
maybe you are using the studio preset?