if in differents diagrams there is the same Class, if in one of the diagrams, I add an Property or an Operation.
In the others, the Property & Operation are not shown...
Is this a bug ?
Is the method wrong ?
In Papyrus, you should always distinguish between the semantic information (i.e. the UML Elements, such as a Class or a Property), and the graphical representation (What is shown to the user). This is not synchronized. It is absolutely possible to display a Class without displaying all its properties/operations. The hidden properties still exist, but they are not necessarily visible.
In your case: you manipulate the same semantic element (A Class with Properties and Operations), and two different views of this semantic element (The squares displayed on your Class diagram).