Hi Kenneth, This sounds like macOS isn't refreshing the cache. Try restarting your Mac.

If rebooting your Mac doesn't work then try to reinstall Firefox. Download a new copy of the Firefox application and save the Disk Image file to the desktop Firefox 60.0.1: *https://www.mozilla.org/en-US/firefox/all/ *trash the currently installed Firefox application (open the Applications folder in the Finder and drag the Firefox application to the Trash) to do a clean reinstall *install the new version that you have downloaded *https://support.mozilla.org/en-US/kb/Installing+Firefox+on+Mac Your personal data like bookmarks is stored in the Firefox profile folder, so you won't lose personal data when you reinstall or update Firefox, but make sure NOT to remove personal data when you uninstall Firefox as that will remove all Firefox profile folders and you lose your personal data. *https://support.mozilla.org/en-US/kb/back-and-restore-information-firefox-profiles

This somewhat resoled itself in the end. Thank you for your suggestions!