Seems like a recent bug but making sure:
For about two weeks now when we add Table of Contents widget to pages (and blog posts), it doesn't always show. Even hard refresh doesn't help - the only thing I find to always solving this is to edit the page, revert to last published version (no actual editing), and then it will appear. But can't be sure it will stay that way upon browsing to this page later.
Is anyone familiar with that?