I don't know what happened but my problem was solved after I did the following :
I tried changing the lock screen to something that looks similar to the login greeter. At first it didn't work.
After a while I had a problem with the panel and launcher not showing up in my account. So I created a new user and I was surprised that the lock screen change worked. So I try to bypass the lock screen and I discover that I can't do it anymore.
In answer to your question: yes I could reproduce it every single time before changing the lock screen.
I don't know what happened but my problem was solved after I did the following :
I tried changing the lock screen to something that looks similar to the login greeter. At first it didn't work.
After a while I had a problem with the panel and launcher not showing up in my account. So I created a new user and I was surprised that the lock screen change worked. So I try to bypass the lock screen and I discover that I can't do it anymore.
In answer to your question: yes I could reproduce it every single time before changing the lock screen.