Import of additional solid volumes into a CAD scene

Using SimScale CAD & Meshing
6

Hi @sjoshi, @AnnaFless,

now I tried to work with faces for MRF but without success. I tried to mesh the geometry 3 times with two different geometry variants but got error messages on all operations.
In the output window in all operations it is written that generate of MRF zone will go wrong for the reason that entity mrf_rear is not watertight. But when I checked the stl model import and also at my CAD tool the geometry is watertight.

If you are interessted to see the project here is the link: https://www.simscale.com/workbench/?pid=2118895847723509960&locale=de#tab_0-0
The result output is to find in Mesh Operation: "Windkanal 4 2 mrf 2

Any ideas?
Thank you very much.