Facebook App Confusion
There's an older app on Facebook called "Nations". Its developers have long since mostly given up on it, and certainly won't be updating the code any time soon, so I thought I should try and outline the problem here.
Shortly after I installed HTTPS Everywhere, I started having trouble with the app. See, I can't access it using HTTPS; it either doesn't recognize me as a returning user and prompts me to start a new game or doesn't connect me with my account, so to speak, saying "[file] not found!" when I try to access my data.
Sometimes the confusion occurs on Facebook's end, as well. While logged in to Facebook, I tried to access the app and was shown the Facebook login screen instead. I had to set a rule to disable HTTPS Everywhere for Facebook Apps, then close my browser and try again for the app to finally recognize me as the returning user that I am, and thus link me up with my data. It's bad enough the thing needs thrid-party cookies to operate...