OK! I finally found the answer as I was browsing through stackoverflow through all sorts of mindmap/primefaces related problems and desperately trying to apply any solution.
Apparently, the ManagedBean/Named bean (if you use CDI) must be @SessionScoped and NOT @RequestScoped (which is by default). If it is @RequestScoped you get peculiar behavior and certain events (in my case the "select" event) do NOT fire.
I do not know whether this is a bug or is carefully omitted out of the documentation. However, someone should document it explicitly!