Adding child to scrollbox not working

Where is “this is my BP” happening? Inside a widget or another type of blueprint? - Sorry, but my english is not really good and I don’t understand the question.
If you were to add “…item” widget to the viewport directly, without adding it to the parent, is it visible then? - Yes, it’s visible.
What does the design tabs of the widgets look like. - Some screenshots:



If we’ll fix problem with invisible widget, I will delete all these buttons and add them in game by blueprints :slight_smile: