Problem with .shell on complex geometry

[wallahi06]

Hey! I face a problem were I get

<ipython-input-22-69fc1cae0e22> in <cell line: 9>()
      9 for obj in result.objects:
     10     workplane = cq.Workplane("XY").add(obj)
---> 11     extruded_objects = extruded_objects.union(workplane.wires().toPending().extrude(80).faces("+Z").shell(2))
     12 
     13 

1 frames
/usr/local/lib/python3.10/dist-packages/cadquery/occ_impl/shapes.py in shell(self, faceList, thickness, tolerance, kind)
   2736 
   2737         if faceList:
-> 2738             rv = self.__class__(shell_builder.Shape())
   2739 
   2740         else:  # if no faces provided a watertight solid will be constructed

StdFail_NotDone: BRep_API: command not done

When I run

import cadquery as cq

result = cq.importers.importDXF("/content/GitHub-logo.dxf").wires().toPending()

extruded_objects = cq.Workplane("XY")  # Initialize an empty Workplane


for obj in result.objects:
    workplane = cq.Workplane("XY").add(obj)
    extruded_objects = extruded_objects.union(workplane.wires().toPending().extrude(80).faces("+Z").shell(2))


cq.exporters.export(extruded_objects, "/content/test/test.step")

It has to do with the .shell() operation, it works fine with -0.1 but I need it to be 2mm and even more If needed. What is the problem with my code? I use a dxf image of the github logo and extrude it to 80mm but I want to make it hollow with .shell(). Thanks!