Hello everyone. I tried to fill a simple cylinder which is made up of 3 knitted surfaces. I tried using the knit and thicken feature but the cylinder always appears hollow in the section view.

Here are the steps I took to make the cylinder:

I started with creating an extruded surface just like in the picture below;

Then, I closed both ends using the filled surface feature

Now I have 3 surface bodies which I knitted using the knit surface feature so I ended up with one surface body.

Then I applied the thicken feature with the "create solid from enclosed volume" checked to the surface body. However, the object still appears hollow like in the first attached image. 

Does anyone have any idea why this happens? Please find the attached Solidworks part file.

Thanks.