Missing model parts and addition of non existing model parts?!

[3Dprinty]

I tried to print this LEGO gear and noticed the following issues:

* The four spokes are missing

all 4 spokes are missing

* A plane is added in the middle that doesn't exist in the original model
* The step inward of the four round holes gets printed with the perimeters first and thus gets printed in the air - supports are not generated either

The original model (t110.stl) comes from thingiverse:
https://www.thingiverse.com/thing:2765212

Nozzel: 0.4 mm
Extrusion width: 0.4 mm

Support generation is enabled but is not generated correctly?
Any advice on what's going wrong here?