World78, your product situation could be caused by a number of things:

Maybe the inserted part is out in space? Try a Fit-All-In to resize everything.

Maybe your Tools+Options are set to cause this. Check them out.

Could you attach a screen shot of your product tree? The icons in front of the parts often provide clues as to what is happening.

Regarding the Partbody problem; does the new partbody you inserted show up in the tree? It's normally added near the bottom.