For some reason, when I have this addon enabled, I can't get the Pinterest website to load. I doubt it's exclusive to just Pinterest but I noticed that every time I try to use the "sign in with Facebook" or "sign in with Google Plus" option, nothing seems to be happening. And even when already signed in, the pins won't load.
This should be fixed at the development channel. I've also uploaded a new stable version on 2017-04-11, but review takes very long these days (Queue Position: 144 of 291). Sorry for any inconvenience.
