Installing .Net 3.5 SP1 Beta is not recommended if you are using the current version of ElementFlow. When you add items at runtime, the corresponding 3D planes don’t show up. However when I check the Children collection, the models do exist. Looks like there are some issues adding GeometryModel3D to Model3DGroup at runtime.
Surprisingly there are no exceptions thrown when I add the elements. I see the following exception only on closing the application. Note that this issue doesn’t arise for the earlier version of the framework.
Here is a link to the text file containing the stack trace.