Can't reproduce Edge 3D effect

What does not work

Can't reproduce Edge 3D effect as described in the documentation and shown in the corresponding figure. This is the 'separate issue' mentioned in inkscape/inkscape-docs/manuals!50 (merged). inkscape/inkscape-docs/manuals#16 depends on it.

Expected output

Image contour3D-w.png as shown on page Extensions (Inkscape-Beginners-Guide/source/extensions.rst).

Tested configurations

Inkscape 0.92.4 (5da689c313, 2019-01-14) on a freshly installed Debian 10.11 in a virtual machine. Inkscape 1.1.1 (3bf5ae0d25, 2021-09-20) on Debian 11 using Bullseye backports.

Steps to reproduce

1. Open new document in Inkscape

2. Create text object: "Test"

3. Duplicate object and move it vertically

4. Object to Path

5. Ungroup

6. Extensions > Modify Path > Edge 3D...

   Edge 3D settings:

   • Illumination Angle: 15.4
   • Shades: 27
   • Only black and white: off
   • Stroke width: 5.0
   • Blur stdDeviation: 4.8
   • Blur width: 5.1
   • Blur height: 6.5

7. Delete underlying objects

Output

SVG source

PNG