Try to check the settings for the section and the column, maybe you have one chance there to hide it. As you can now "freeze" one column and scroll another one that scroll bar is the one of the column (I guess), if you click to display all result the scroll will happen on the "inner" scroll, not the one of page (the one on the right), as far as I remember.
Now sure it's a problem, it's more the normal way to support advanced behavior in a dashboard with multiple columns / sections.
There is no way to hide scroll bar from Column/Section settings.
Have you any workaround to solve that? I never experienced that until now.
Any help will be appreciated.