Рейтинг 1 из 5 звёзд

68.4.1 Works through time. Reinstalling the plugin temporarily helps.

It works for me on both Windows and Linux (including after restarts). If the issue only occurs after some time, the issue might be a varying order in which add-ons are loaded (especially if you use other add-ons influencing Thunderbird's main window). It thus might be able to fix it by disabling the conflicting add-on (and/or telling me which add-on is in conflict through the email listed as support contact).