Soften Edge made all faces of cylinder connected

Hi Experts,
I am using those C APIs to write out sketch up files. since my output data is tessellated mesh, I googled and found soften edge can help “connect” facets, so I called following codes when create a LoopInputRef item.

for(int i = 0; i < 3; i ++ )
    SULoopInputEdgeSetSoft(loopRef, i, true);
    //SULoopInputEdgeSetSmooth(loopRef, i, true);

After this I found a cylinder model all faces(top, bottom and cylinderical face) were connnect and single click will select all faces. What I want is can act as native sketchup application’s selection behavior for a cylinder body(3 faces selectable).

And even worse this model can’t be re-soft by the sketchup application when select all faces and righ click->soft edge…

2.skp (21.7 KB)

Could you help take a look?

Use these tools to see and work with the edges…

View > Hidden Geometry
View > Face Style > Wireframe

Eraser + Shift = Hide Edge
Eraser + Ctrl = Soften/Smooth Edge
Eraser + Ctrl + Shift = Unsoften/Unsmooth Edge

Window > Entity Info = Entity Info Dialog Box

Window > Soften Edges = Soften Edges Dialog Box