MD-Solids is the term for Solids that you add with Add Profile/Auto-Profile, and
CAD-Solids is the term for Solids that you import onto a CAD-Line.
The commands in the Solids menu and Solids toolbar relate to MD-Solids
To see MD-Solids and CAD-Solids, you must enable Visibility toolbar > Show Solids in Mechanisms
The Solids toolbar is above the graphic-area