Windows Pin Keyboard does not work on particular user profile

My daughter's pin on Windows is not working to log in. When she tries to log in she can only enter numbers - that is to say the number keys on the keyboard work but none of the letter keys work. When she has tried to log in too many times it stops working and puts up the message that she should enter in a particular key sequence to allow her to try again. When this screen is active she can enter in letter keys. As soon as it goes back to password field it is again only allowing her to enter numbers. If we switch to my account on the computer I can enter both numbers and keys and log in on my a

Question by user254694 on Super User, licensed CC BY-SA. We show a short excerpt and link to the original thread as credit.