Facebook button "doesn't click" on Firefox. It works on Safari. And both the Google buttons and standard email buttons work on Firefox. Of course, I could have logged in using Safari. But my pedantic nature won't let me drop it. The button obviously works, so the problem must be on my end.
MY BLIND STUMBLING
I remembered I'd just had an Adobe update, so I reinstalled Flash. Then, since I run LittleSnitch (it's a program with stops traffic) I checked all my rules. I didn't see anything, but just in case I opened everything up marked "adobe", "firefox", "facebook", "khan academy" and even "youtube".
Nothing, not a blink. Same problem. And I rebooted my computer about a dozen times. And then I looked through about a bazillion things I shouldn't have, using a search engine, but at least I'm smart enough not to go deleting bits of code and random processes in my computer...at least, not lately. *looks innocent*
Of course, I put back all of my exceptions in LittleSnitch after that, but I did take the time to delete some stuff that was old. After all, no point in keeping an exception for Zynga and Playfish when I know longer play games from those companies.
Then I went for help.
At most this took 15 minutes. As I said, probably it took 5, the first 2 of which were me showing him what was wrong.
Still, I need my privacy add-on, because I'm a crazy person. And, from the depths of my brain, I vaguely recalled an exception I'd put in for Khan Academy, but I couldn't remember how I'd done it. They had, however, changed their login screen, so I thought maybe it had deleted the exception. I also recalled that there was an icon for my privacy tracker, which should have been on my toolbar, but was missing.
So I went to the website, only I couldn't remember my password. Spend 20 minutes getting frustrated because I also couldn't remember exactly the email I'd used, and for some reason couldn't get a new password. Turns out, I was at the wrong site. I'd searched for the name "Do Not Track Me" (which is the name of the plug-in) on Google, and that actually brought me to NIA, which is a scammy little company that happens to own a good domain name. Luckily, LittleSnitch stopped THEM from requesting information. I should have known something was wrong when it popped up two items, one of which looked like a tracker. Do NOT go to the DoNotTrack Opt-Out website, because it has ad trackers on it. Figures.
Anyway, I went back to the plugin manager and found out the place I was looking for was https://abine.com/ They had more helpful tips for recalling the Firefox icon, except that for whatever reason the icon in Firefox wasn't blue, so at first I didn't identify it when I went searching. I almost uninstalled it and reinstalled it (the nuclear option, as they say).
After that, it was easy. You just put in the exception from the icon. So now I have Khan Academy AND my privacy add-on working. YAY!