<figure> Horizontal Scrolling Doesn't Work When Parent is <fieldset>

[leoherzog]

I need to dynamically show/hide a <figure> horizontal scroller containing buttons, along with it's corresponding <label>, together as a group in a form. If I wrap the <figure> and <label> in a <fieldset>, then the horizontal scrolling no longer works. It works fine if the parent is a <div>.

https://jsfiddle.net/leoherzog/1a9jwe58/2/