In Veyon 4.11.4, sharing a student's screen using the context menu behaves differently from using the Demo menu in the toolbar.
When "Share selected computer" is launched from the context menu of a student thumbnail, the shared screen is displayed only on the master computer.
When the same student computer is selected and "Demo → Share selected computer" is launched from the toolbar, the screen is correctly broadcast to all client computers.
This behavior is reproducible and seems inconsistent.