UMG scrolling probblem of scrollbox in mobile

I am making a UMG which include a scrollbox.
Inside the scrollbox, I have a wrapbox and contains a gridbox.
In the gridbox, I will programmatically add buttons to the gridbox,
so that I will finally have a grid of buttons.
Now I am facing a scrolling problem in the above setting.
I can scroll by dragging my finger in the empty space inside the scrollbox, and between the buttons.
However, I cannot scroll if my finger first touch on one button and then drag.
I found that my finger touch will be consummed by the button first, but not the scrollbox,
that leads to scrolling can applicable in the space between the buttons.

Can anyone tell me how to solve the problem?
I expect I can scroll even my finger touch the buttons first.

Thank you.

Buttons Touch Method needs to be set to Precise Tap.


Thank you so much!