Hello,

I haven't released new version for a long time now so this is most probably related to something in your Firefox profile (since so far nobody else is reporting this).
You can try to reinstall my add-on (make sure to export your dials to a file first), but it that won't help, I would suggest you to use Firefox Reset - this often fixes many profile-related bugs:
https://support.mozilla.org/kb/refresh-firefox-reset-add-ons-and-settings
Resetting profile will preserve your passwords, bookmarks and other important things (but not add-ons data).
Before resetting your profile I would suggest you to setup Firefox Sync. - this will backup the list of installed add-ons and after reset it will reinstall them.

Feel free to contact me to my support e-mail if it didn't help (of if it helps).

Best regards,
Juraj Mäsiar