OK - it looks like the problem was down to ignorance on my part as I did not understand the contexts where EJB injection is permitted.
The EJB (MockDataProvider) is instantiated by the container and injected into the DashboardView class which, as it was annotated with @CDIView, is also managed by the container. Hence, everything works fine. However, the Chart object was not container managed (despite my misguided addition of @Dependent to try and get the container to "notice" it) - injection into POJOs is not permitted but appears to fail silently which only added to my confusion.
Granted, the code structure is pretty appalling (close coupling, highly dependant and no separation of concerns) and this shoddy approach to prototyping has been responsible for creating the issue. Passing the Charts object the data directly or a via reference to the EJB via a constructor call works without problems.
Good job your learn from your mistakes. At the rate I'm making them, I'm going to be a genius!