You no longer see installed extensions, known as add-ons in your latest version of Firefox.
To fix this annoying issue, follow those steps:
- Close Firefox.
- Click on Windows button + R.
- When run appears enter:
- Navigate to the profile.
- First create a backup of extension.ini and extension.sqlite.
- Now permanently delete extension.ini and extension.sqlite.
- Restart your Firfox browser.
Firefox Addons Manager should now be restored and working.