I am not sure what I did but the extension is now working perfectly.
I will leave my comments below just as a reminder that hope is not lost.
This would be a great extension for Firefox if it would just work. I have installed the extension but when clicked it only pops up and immediately closes. Please help. I am using Windows 10 Home.

great tool to share for groups

FF 60, window opens and closes immediately. Unusable.

I love Share Button Facebook by Baris Derin Thanks a lot Recommend to everyone :-)

Used to work great but now the window flashed and disappears. Tried removing then re-adding the addon but still does the same. I'll miss this addon.

Funktioniert leider seit Monaten nicht mehr.

nÃO FUNCIONOU POR AQUI.

Still not closing window under FF 57.

As noted previously by other posts, under FF 57, the addon opens a window the same size current browser that does not close after submission.

très long transfère sur 3 étapes

Suggestion: Option to open in a new tab.

Since the last update the window opens at the same size as my primary window and then doesn't go away. That's Firerfox 56.0.1