When a user clicks the pencil icon to edit an experience, that experience becomes locked and remains locked until the user navigates to another screen or closes the browser.
Anyone trying to edit the same experience, or to change its state will be presented with a modal, explaining who is currently editing.
Similarly, if you have multiple tabs or browser windows open and try to edit the same experience in two places, you will be locked out.
The purpose of this lock is to prevent accidental overwrites, where the last person to save undoes the changes saved by another user.