Why is the class not displayed?
It’s a private class used to style the default class clean option in Blocs. Did you input that class name?
I have inserted the class with the Classmanager - Subclass Lip - Buttons - Button clean.
But I found today that it is obviously related to the backflash. If the text does not contain a backslash, the class appears at the top right. If it has a backslash, the class disappears at the top right.