Jon
You happened to pick one of the few cases where this is an issue.
The fix to go back to hybrid after your done the roation is easy:
From the Resource Browser, Edit > Edit 3D.
Once inside the edit space, switch to top or top/plan view then draw the lines and rectangles you want to be used in 2D. Exit the symbol.
{This means, of course, you can't rotate the symbol again!}
Try to edit the 3D part of the symbol again, and the 2D stuff you just added will be gone. They found their way home to the 2D part.
One way around this is to take a 3D only truss, rotate it to taste, and create a 3D only symbol. Then insert that symbol (as just a 3D symbol) onto your drawing. Draw 2D geometry over the top of it. Select both the 2D geometry and the 3D symbol and create a new symbol. Convert that second symbol to a light position.
Now you can still change the orientation of the truss in the original 3D symbol and it will change in the 3D part of the position object - without having to keep going back and forth from hybrid to 3D.
Hope that makes sense....
michaelk