So to summarize it to anyone who is not getting deep into this thread:
You have a Morph and a Wall placed on Story 0.
They both have their Show on Stories option set to All Relevant Stories.
The top point of both is below the level of Story 1 so they do not intersect the level of Story 1.
You go to Story 1.
In the Floor Plane Cut Plane Dialog you set the Show Down to field to 1 Story Below. So in Story 1 you want to see elements placed on Story 0 (Story 0 is their Home Story).
The Wall will be visible on Story 1. The Morph will NOT be visible on Story 1 with the above settings.
One would assume that since the Morph is set to All Relevant Stories, and since the Floor Plane Cut Plane Dialog is set to show elements on 1 Story down, the Morph, being on Story 0, should show on Story 1, just as the Wall is shown.
But the Morph does not show.
I am going to report this to Graphisoft. Meanwhile, I think you should be using the solution alexwang32 has given you.
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