I know the fix but I'm trying to figure out where this issue falls in WCAG 2.0.
When the webpage loads there is a scroll effect which hides the main content of the page until the user navigates into it. The issue this causes is that when SR users open their utility menu before they navigate through the page, the headings (and other things) in the main content region don't show up because in the utility menu because they aren't visible yet. Once they navigate into main content the headings show up.
I'm leaning towards the "Multiple Ways (Level AA)" but my holdup is this seems to apply more to the site-wide navigation rather than page navigation and there is more to this. The other option is something under parsing but I couldn't find anything that specifically applied in the success criteria.