Thanks for trying but that’s not the point.
I do not have the project (I was proving the point in my original answer) and I am reluctant to set it up again since I know UMG well enough to tell when things are fishy. (or that the time spent setting it up and making it work is a poor payoff). It’s not the first time I’m hitting UMG limitations/bugs.
I mean, the very fact that the list view ignores the widget added to the panel and creates its own instance from defaults tells one a lot about the functionality. Whether it’s indented or not.
Lets say I want to add an instance of a widget to the list view dynamically. I will feed the list a fancied up child but that will get ignored because the list view will then create its own version from class defaults. So I need to find in the list and push the data back it again? No, thank you. 
Don’t even get me started on trying to insert widgets into panels.
For the sake of clarification, this does absolutely nothing in BP, for example:
I am under the impression that this widget shouldn’t have been exposed to blueprints in 4.20. On the other hand, if this is the intended functionality, I do not wish to have anything to do with this widget 