The bulleted list under “Watch for Symptoms” at the URL has the items laid out in 2 columns, but the bullets are laid out in one column, overflowing the list.
Created attachment 460952 [details] Web archive
Created attachment 460953 [details] Test reduction
Those bullets are not the actual <li> bullet points. They are out-of-flow before content.
(In reply to zalan from comment #3) > Those bullets are not the actual <li> bullet points. They are out-of-flow > before content. which means they are not part of the column context (ie. the before block box's containing block is the RenderView (ICB) and not the RenderListItem)
<rdar://problem/97486383>