Embedded WebExtension icon only visible after page refresh

Our WebExtension icon is embedded next to to-dos, milestones, issues in apps like Basecamp, GitHub, JIRA, etc. Clicking icon launches an embedded panel with more content and functions.

Expected behavior is that the icon is always displayed. Only recently has this behavior changed and the icons are not displayed. Using a Basecamp project for context, suppose the To-Dos page is bookmarked:

  • Icons display if To-Dos page launched from bookmark.
  • If user navigates to Discussions page (in same project) then returns to To-Dos, icons are no longer displayed.
  • Manual page refresh always resolves issue and icons are displayed.

Please see attached animated GIF for visual reference.

The issue is limited to Firefox (Chrome and Safari work as expected).

Thanks in advance for any insight or feedback!

Have you checked if your context script is initializing properly on first load, e.g. gets run too early or late?