ScrollBox can't be scrolled in a 3D widget on mobile device

1. Create a simple Project.
2. Create a UserWidgetBP and add a ScrollBox in it, add some buttons to the ScrollBox.
3. Create an ActorBP and add a WidgetComponent, set the widgetBP created the last step.
4. Set "receive hardware input" to true in widgetcomponent's detail panel.
5. Add the ActorBP to level.
6. Package the project and launch it on mobile.

The scroll box can't be scrolled with touch input.