Do MessagingCenter subscriptions get processed on not visibale pages

I have a page that includes a control, this control has a view model that subscribes to a message Like this

MessagingCenter.Subscribe<object, string[]>(dummy, "UPDATE_LAST_SYNCED", (sender, values) => { setSyncFromMessage(); });

in the constructor. This page then open another page, from in this page I Update various things and Issue an Update Last Synced message.

I have a Break point in the Function "setSyncFromMessage" an it does not get triggered, should it?

any ideas