I've finally sorted this out. The OrangeRX TX Module supports 4 different modes DSM2 1024/22ms, DSM2 2048/11ms, DSMX 22ms and DSMX 11ms.
When you bind the model it binds to the mode that is most appropriate for the RX and the module flashes 0 to 3 times depending on what mode you bound. In my case, I have two orange RX's and one binds at DSM2 22ms and the other binds at DSM2 11ms. When I switch between models, it turns out that you have to push the bind button on the back of the TX module three times quickly to switch the mode otherwise it will appear that you have lost binding.
I believe that you also have to set the 9xr to the correct saved model before you power on the RX.