When you add more than one workpiece to a milling simulation, only the first one will be solid.
All additional ones will be shown as transparent ghost- like workpieces.
This is a limitation in how the workpiece buffer work in the simulator, and it is also to protect from out of memory errors as a workpiece buffer takes up lots of RAM and CPU resources.
If you have a powerful computer that you think can handle this, there is a workaround.
You can simply make one large workpiece that you cut up to smaller pieces with a simple CNC program. Then you can save this as a prefabricated workpiece and use it in your projects.
