Update 20.0.1 Rated 5 out of 5 stars

Same issue, choices disappear from Add-On bar, but still available in menu and context menu.

This review is for a previous version of the add-on (0.92.00.1-signed). 

As I wrote in version information I removed the code to show it by the options panel.

You can move the button in the addon bar by using the standard customize of firefox.

Thanks for your report.
FD