Path: cannot create 3D pocket: shape is not planar

Mods CAM/Path
1

I have a model with two identical parts. I can make a 3D pocket for one of them, but cannot make it for the other.

Is it a bug, or I do something strange? Any ways to work it around (including hints on the nature of the bug and approximately where to fix the code)?

The error message is below. I have attached the (simplified version of) the model, with the path existing for the part which I could create it.

Reproduction:

  1. Select the 3 shapes (top of two lying cones and one cylinder) for the other part
  2. press the 3D pocket in Path workbench
  3. press Apply in Tasks.

I have EnableAdvancedOCLFeatures and EnableExperimentalFeatures parameters set to true in BaseApp/Preferences/Mod/Path.

Error message:

19:32:51  {'sclassname': 'N4Base10ValueErrorE', 'sErrMsg': 'shape is not planar', 'sfile': '', 'iline': 0, 'sfunction': '', 'swhat': 'shape is not planar', 'btranslatable': False, 'breported': False}Something unexpected happened. Check project and tool config.Traceback (most recent call last):
  File "/usr/share/freecad/Mod/Path/PathScripts/PathUtils.py", line 71, in new_function
    res = function(*args, **kwargs)
          ^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/share/freecad/Mod/Path/PathScripts/PathOp.py", line 820, in execute
    result = self.opExecute(obj)
             ^^^^^^^^^^^^^^^^^^^
  File "/usr/share/freecad/Mod/Path/PathScripts/PathAreaOp.py", line 423, in opExecute
    raise e
  File "/usr/share/freecad/Mod/Path/PathScripts/PathAreaOp.py", line 417, in opExecute
    (pp, sim) = self._buildPathArea(obj, shape, isHole, start, getsim)
                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/share/freecad/Mod/Path/PathScripts/PathAreaOp.py", line 228, in _buildPathArea
    area.setPlane(PathUtils.makeWorkplane(baseobject))
<class 'ValueError'>: {'sclassname': 'N4Base10ValueErrorE', 'sErrMsg': 'shape is not planar', 'sfile': '', 'iline': 0, 'sfunction': '', 'swhat': 'shape is not planar', 'btranslatable': False, 'breported': False}

Version information:

OS: Debian GNU/Linux 12 (bookworm) (GNOME/gnome)
Word size of FreeCAD: 64-bit
Version: 0.20.2.
Build type: Release
Python 3.11.1, Qt 5.15.8, Coin 4.0.0, Vtk 9.1.0, OCC 7.6.3
Locale: English/United States (en_US)
Installed mods: 
  * Curves 0.6.22
  * A2plus 0.4.61