Unable to see widgets added to scroll box

Hello, I’m currently trying to create a dialog system, so I’ve more or less followed a YouTube tutorial.
(- YouTube, - YouTube and
- YouTube)

So I can see the responses of the character but I’m unable to see the answers buttons !
I only see and empty Scroll box but I’m sure the answer buttons were added because I can printstring their text and I can see that the child count was increased.
What could I missed (I’m on this bug since several days and I still don’t find any working bug fix).

I just do a Create Dialog Button Widget of my button then Add Child (myscrollbox, mybutton).
I’ve checked visibility (scrollbox is visible any way).
My dialog button is a widget bluprint containing a clickable button with a text.

hi, any debug hint would be great :wink:
I’m going to create a small project to debug easily, but maybe I’m missing something obvious in my create dialog process ?