Auto Fill 'fills' but does not work

I can login to my Identity Safe Vault and have loads of saved logins.

When I go to web pages which require a 'login' the login details, normally 'user name' and 'password' are automatically filled in.

But when I click a 'login' button it gets rejected.

Let's say my User name is 'admin' and my password is 'London'

If I delete the last letter of my user name, in the case the  'n' and re-type it in, and do the same with the last letter of my password and then click the 'login' button, it works.

So I don't have to re-type the whole user name and password, just the last letter of each.

This hasn't always been the case but probably for the last couple of years, I've just not got around to finding a solution.