I have an assembly and I found out its center of mass by applying density after converting the assembly file to a part file. After having scaled down the part I am unable to apply density to.
@De_3d, How did you scale it? Part copy I assume. It works for me meaning I can change density.
Is this your workflow?
1. In a new part insert a part copy of the assembly.
2. Save that part
3. In a second new part insert a part copy of that part with a different scale than 1.
I'm not sure why scale would matter. A scale of 1 is also a scale that just happens to be 1.