Prepare Vs Preview Slicing question

I am a novice at best here but I want to understand better how the Prepare view of this STEP file looks solid and then when I slice it and look at it in the Preview view you can see the mesh and circles that result. Why would that be? Is it a design issue OR is it SLICER settings.

Any time you can spend teaching me is greatly appreciated.

Thanks,
Joe D.

Again I am new to all of this but this is what the design .STEP file looks like in Fusion 360. Thoughts or Ideas?

In the Preview tab, I think the vertical slider on the right side of the screen has been lowered, so that you are seeing the sparse infill of the model (the square grid) and the walls around the holes, several layers from the top.

Drag the “+” all the way up to see that the top surface will be solid where you would expect.

The slider will be at the top after the model is first sliced. If you slide it down to look at a lower layer, then change a setting and re-slice, the slide will be at the same lower layer as before.


Another possibility is that in Process settings / Strength / Top/bottom shells, the Top shell layers have been set to zero.

Not sure if I follow you 100% but just to be clear when I print the project the print turns out just like the Preview shows. That is kind of my concern I want the physical result to be more like what I see in Fusion 360 or the Prepare image.

Thanks

I was editing ( my bad habit) as you were responding. If it actually prints as shown, then zero top shell layers is more likely the problem. Or zero bottom shell layers if we are looking at the bottom of the model.