Ipywidgets won't make it to html download


I have already posted this question as a digression in this post because it looked like its author had my answer already, but that did not pan out so I am trying my luck another time here

this is about notebook classic; in a nutshell I have a notebook that produces ipywidgets; for example

as you can see, nothing fancy, only text html tags embedded in a grid
If at that point I try to download the notebook as html, I am getting this; the widget has gone

From what I had read in nbconvert's changelog for 5.5, I was hoping this to work smoothly, and so my questions are

  • am I right that this should work out of the box ?
  • if so, what can I be doing wrong ?
  • if not, is there a way to get this work ?

thanks in advance