Profile page has this section at the bottom:
When I am logged in, clicking on All/Questions/Answers or Votes/Newest will filter/sort accordingly, and the orange highlight (colour may vary according to site) will shift to show the currently selected item.
The bug manifests itself when I am not logged in. In this case, clicking on Questions or Answers or Newest will successfully filter/sort, but the highlight will momentarily move to the selected item and then go back to the defaults, i.e. All and Votes. Now since the highlighted item cannot be selected again, this means if I filter/sort using any of the other options, I cannot show All Posts and Posts sorted by Votes again.
In short, while not logged in once Questions/Answers/Newest have been selected, one cannot select All/Votes again since the highlighting is broken.
Bug confirmed on many SE sites (must affect all since it's common code). Checked with Firefox (Windows) and Chrome (Android).