Mapper devices do not create any tree nor children


when creating mapper devices, no children, no nodes, no mappings are created.

Even if I use the prebuilt examples (Mapper, Timer) or if i paste examples from the docs, any mapper devices just always look like this:

I would expect that the mapper in the GUI would have some children - node and sensor. As it is shown in the docs. The problem is that no children appear.

Am I doing something wrong?
Or is it as it seems that “mappers just do not work at all”?

I searched github issues, google and this forum and I saw no records about this.
Tried on Win 10 and Mac OS 10.15.7

Thank you for any advice…