If you could upload the model, I could probably tell you more. I suspect the density of the Solid is zero, and typically that happens when the material property of the parts has not been specified in the CAD system. You can set the Density parameter in the Simscape Multibody Solid block to see if that would solve the problem. If this solves problem, make sure you assign the material in SolidWorks. However, the location of CG seems like a much bigger problem, and that certainly looks like a problem created within SolidWorks.
I have tried bringing the parts into Simscape Multibody in three ways:
- Referencing the STEP files directly
- Via SolidWorks
- Via Onshape (had to select material manually here)
In all three cases, the parts were positioned and oriented properly, and had mass and inertia defined. Screenshot from SolidWorks and Onshape is below.
I hope this helps.
--Steve