Twitch forced me to reset my password, which also reset my stream key. I unbound my account from Twitch and the Mojang account page, as instructed (over 24 hours ago). And then I rebound the accounts per instructions (over 24 hours ago).
However, when I try to click the Broadcast Settings button inside of Minecraft, I am still getting the error: "Twitch Broadcasting Unavailable. Authentication to Twitch failed. Please go to mojang.com and rebind your Twitch account."

I've searched this database as well as Twitch support and a google search and am unable to find a solution.