VTK Slice example NOT working

I am not able to run properly the VTK example:
as properly represented in the picture of the PANEL gallery webpage (a panel + 4 VTK floating sub-windows:

I am under linux (same problem with firefox and Chromium)

Any suggestion?

Thank you in advance!

More informations would be welcome (run in notebook, bokeh server, javascript errors, panel version, bokeh version,…)
I just tried in a notebook, I’m on unbuntu chrome and there is no error:

this is what I get under Xubuntu 20.04 LTS, just opening this page:

Firefox 87.0 or
Chromium 89.0.4389.90 (Official Build) snap (64-bit)

It’s a bug in the doc you should open an issue on github