I just double checked. It was indeed from the ui_table example that I've disabled 
As you can see in the properties of that node "Property" and "Title" is set to id.
Maybe there's a small blurriness in the code of ui_table.. (@Christian-Me: I avoided "your" )
Offtopic: However, my new Node-Red version still does not want to start, but this time there are no errors on the log. I'm probably missing some detail somewhere after building my custom docker image (I need Node Red with a Node.js version >= 12). But I'll dive into those problems another evening.
Wish you all a good start into next week!
Cheers,
Marcel
