I need your help!
Shape A is able to SVG, but unable to export pdf, jpg, gif and png.
Shape B is made from A by Join in Operation, and has no problem.
The icon of Shape A is invisible in drawing stencils window.
I compared the shapesheets of shape A and B, but could not found any difference.
What is the reason?
The first shape has "non-printing shape" flag set. it looks like picture export excludes shapes with that flag.
To figure out, I've saved as .vsdx, then compared master1 to master2 side by side:
Thank you for all, Nikolay.
My problem solved completely!
Perhaps I corrupted that property,
when I was making shapes using a protected drawing
by the new feature of Visio 2016.
Thank you again.