This workaround has been tested on Windows computers only. It might not be needed on Linux and macOS.
- Type about:config in the address bar and press EnterReturn.
A warning page may appear. Click to go to the about:config page. (For more information about this page see Configuration Editor for Firefox.)
- Search for the security.osclientcerts.autoload preference and change its value from false to true by clicking the Toggle button.
- Close the about:config Advanced Preferences tab.
(More technical details about this can be found in bug 1636100.)