Try resetting the browser or reinstalling the extensions.

You can check for problems with the extensions registry files in the profile folder. Try to to reset the extensions registry and rename extensions.json (extensionsOLD.json) and rename/remove previously used extensions.* files like extensions.ini and extensions.sqlite when present and rename/remove compatibility.ini in the Firefox profile folder with Firefox closed. *https://support.mozilla.org/en-US/kb/Profiles New files will be created when required. See "Corrupt extension files": *https://support.mozilla.org/en-US/kb/unable-install-add-ons-extensions-or-themes You can check for possible updates in case of issues. *click the cogwheel button (left of the Search bar) on the about:addons page to "Check for updates" If this didn't help then delete add-ons.json and possibly prefs.js in case there is a problem with preferences.

here's screen shot