3D Boundary Layer generation problem

General
1

Hello,
I am trying to generate a 3D mesh with a Boundary Layer.
If I generate a simple 3D mesh with no boundary layer and no BL parameters, I can manage to generate a good tetrahedral mesh.
However, whenever I add the BL, it seems that additional elements are created, all sharing the origin as common node (at coordinates (0,0,0)).

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image835×547 34.6 KB

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image642×462 112 KB

Can anyone help me, please?
Here is my code snippet:

from ngsolve import *
from netgen import stl

mp = netgen.meshing.MeshingParameters(maxh=6e-4,)
geom = stl.STLGeometry('fluid_DomainExtended_remeshed.stl')
bl = [2.67e-6]  
for i in range(10):
    bl.append(bl[i]*1.1)

bl_p = [netgen.meshing.BoundaryLayerParameters(boundary=".*", thickness = bl, 
                                               #disable_curving=False,
                                               #grow_edges=False,
                                               limit_growth_vectors=True, 
                                               domain=".*",
                                               )]

mesh = geom.GenerateMesh(mp=mp, boundary_layers=bl_p)
mesh.Export(filename='test.mesh', format='Neutral Format',)

Thank you so much in advance for your help.