Why are some of my students' diagnostics locked?

When resetting the diagnostic directly from the Current Level Chart on your Teacher Dashboard, you may find some students have a padlock next to their name. This means those students already have a diagnostic in progress. 

The diagnostic automatically appears on the Student Dashboard of any student whose diagnostic is incomplete or hasn't been started yet, so you can reset the class' diagnostics as you would normally without having to take any further action for the locked students. They'll be able to see their diagnostic when they log in!