I was just having this issue. I couldn't log into any of my accounts. Obviously I got back on now, but this is my main account that I was trying to log in with the most.
I use Firefox
I usually click "remember me" but this time that I just logged in, I didn't check it.
And yes I have autofill for the password, if you mean that it automatically places your password in place when you add the username. (But I should note that I did type in my password and username manually too)
I did try to reset my password, and that seemed to be working fine, but it didn't let me log in after that either.