I started having this problem about a week ago. I found that if I click on “I forgot my password” then just close down the box that pops up, I can suddenly log in fine. Making the password visible showed me that for reasons unknown the numbers in my password were showing as if I was holding down the shift key. However the letters in the password were as they were supposed to be. I have no idea why this suddenly started. It’s annoying, but for now I have a work around :/