Works fine. You've likely placed the scroll view into the vertical box and set the slot's Size Rule to "auto" (the default). Auto means, take as much space as you need. If that's the case the scroll bar can never appear because the control will always size to be the size needed to display the content.
Change it to fill and it should work.
A scrollbox no longer gives the user the ability to scroll after being placed in the following widgets.
Head over to the existing Questions & Answers thread and let us know what's up.