Password change at log in not working

I logged in to a remote computer and it asked to reset the password for the local account after logging in. 

I entered the old password and then pasted a generated one from Lastpass into the fields. When I hit enter to move on, it cleared the boxes and asked me to do it again, except now neither password is recognized as the old password. 

This happened once before with another client but luckily I was able to use a different login. Has anyone else experienced this and if so how do you prevent it from happening?