Is this project something that you could send to us? It would probably be very easy to figure out if we can take a look.
Based on the errors you’re seeing, my initial recommendation would be to make sure that your Mapping actually matches your JSF Beans names and parameter values, that your beans have appropriately named getters and setters, and that the values are not being cleared out before the render_response phase.
If you can’t send your project, if possible, could you create a small 1-page test application that you could share with us?
This functionality is working in our regression-test applications.