Hi @ValeriaJMP -  If you save a journal to a file, it loses interactive behavior.  The contents of the journal will be the same as what you are seeing in the JournalBox() script.
The script below demonstrates similar cases using (1) a journal (2) a report.  For most cases with live platform objects, I expect that the report document will be the preferred way to go.
 
// This puts a live platform in a Journal window.  When journals are saved and
// reopened, interaction in the saved journal is more limited
dt = Open("$SAMPLE_DATA/Big Class.jmp");
w = New Window("journal",
	<<Type("Journal"),
	Outline Box("Dashboard",
		Text Box("Custom journal created from JSL"),
		dt << Run Script("Bivariate")
	)
);
script = Get Session Script(w);
w << Close Window;
Wait(1);
script;	// the script will run, but the platform is a clone of the original
// If you do the same thing in a report window, it will retain interactivity
dt = Open("$SAMPLE_DATA/Big Class.jmp");
w = New Window("report",
	Outline Box("Dashboard",
		Text Box("Custom journal created from JSL"),
		dt << Run Script("Bivariate")
	)
);
script = Get Session Script(w);
w << Close Window;
Wait(1);
script;	// the script runs, and the platform is live