Context Menu component demos are not working when navigating from other page

[bwajtr]

This one is a bit tricky to reproduce. When you go directly to Context Menu Component page, then it cannot be reproduced and the context menu opens fine. However, using the steps below I was able to reproduce the issue repeatedly:

1. Go to https://vaadin.com/docs/latest/
2. Using the left navigation menu go to Components -> Menu Bar component (maybe it can be reproduced also when visiting a different component, but with Menu Bar it works for me)
3. Wait until the Menu Bar component demos are loaded and visible (I'm using the Flow variants)
4. Using the left navigation menu go to Contextr Menu component
5. Wait until the Context Menu demos are loaded and visible (also using Flow variant)
6. Try to right-click the first demo
7. Expected: A context menu should appear
8. Actual behavior: The context menu is not visible. Instead, only a small "circle" is shown: