Saved Stories header disappearing in Web App

I’ve noticed this problem over the last few weeks, but finally captured it occurring.

I typically navigate using the keyboard shortcuts, and when saving/un-saving stories with ‘s’, I’ve seen the Saved Stories header in the left pane disappear and sometimes re-appear.

This is on a Windows machine, in both Chrome and Edge.

The animated screenshot attached shows the behavior, while I’m repeatedly pressing ‘s’.