Scroll box doesn't scroll inside the box

I have a real problem with the scroll box umg.
In editor it works correctly.
In build, there’s a bug when I drag the scroll bar. It doesn’t scroll when I drag it into the scroll box, but it does when I continue to drag outside of the scroll box. More precisely, up the scroll box, always at the same height from the actual scroll box (something like 300px upward).
I use 3D widget for that.
Here’s two gif so you can see the bug in action

In Editor :

In Build :


I have seen a similar bug when running my built game in windowed mode. Does the problem go away when you are in fullscreen? If so, try either enforcing fullscreen or enforcing aspect ratio in windowed mode (I think both are in project settings but not sure)

I’m running the game in fullscreen mode. You have the bug only when you run the game in windowed mode?
And how do you enforce fullscreen? I don’t find it in project settings

Specifically my problem was that the mouse cursor shows in a different spot than where it is actually hovered / clicking, so I have to estimate where it “really” is and move it up and to the side away from the button until I see the button highlight (if I were trying to click a button, for example).

I noticed on yours that your scroll box is a little rotated (probably for stylistic reasons). Does the problem go away if it is not rotated?

I see, it may relate to the same issue, But in my case, the hovering / clicking is good, it’s the scroll bar’s scrolling “mapping” that’s messed up.

Unfortunately, if I change it to be facing the camera it doesn’t eliminate the problem.
However, I tried to change the custom size of the widget, in the widget designer itself. And it seems to be changing the way the scroll bar reacts. The scroll zone has moved. Without really fixing it though.

I might think that if I don’t use a custom sized but a full screen widget, it might solve the problem. I didn’t try it yet, I will tomorrow.
The widgets are part of the editor when in PIE right? So it could explain why they can be messed up in build. Since here’s no editor anymore, so they should exists or be emulated somewhere else. I don’t know, just supposing…

How do you have the scrollbox widget anchored? Is it anchored to the corner of a Canvas?
in PIE your screen dimensions will usually be different than when playing fullscreen, so if your widget isn’t anchored to something that adjusts with the screen then maybe that’s why it’s getting messed up?
Is the scrollbar another separate widget or part of the scrollbox widget?