The AddThis Blog states that Facebook does not honor the "URL to share" specified in the AddThis configuration, and I have followed the instructions to add OpenGraph meta tags to the page whose URL I want to share.
I have confirmed via the Facebook Debugger tool that these tags are valid.
However, if I try to share a password-protected staging URL, it works in Twitter and elsewhere but not Facebook. Facebook tries to share the login page for my site; I bet it's trying to share the origin page (where I'm trying to share from, which is a password-protected internal page, so trying to access it prior to login bounces you to the login page).
How can I get this to work how I want?