But they are supposed to. That's the purpose of the slave RC, but I don't have to tell you that. (OK. I'm frustrated.)

I followed the "master/slave" tutorial many times:  

As far as I can tell, all the soft/firmware are up to date:

DJI Go App version = 3.0.0
Aircraft version = 1.9.1.30+
RC version = 1.7.40
Camera version = 1.9.1.10
A9 PLUS version = 01.15.18.09

Here's a clue. In the Go app, I get this message:  Aircraft Status > Overall Status = "Firmware Upgrade Required" > "Camera requires Upgrade. Refer to the tutorial in Academy."

I looked "everywhere" and I haven't found a firmware update for the Zenmuze XR5. (I upgraded the firmware on the copter and RCs and received no errors.)

Any ideas would be sincerelly appreciated. Thank you.

For your slave RC, you would need to "request control" via the RC section of the Go app when you're setting up the slave. That will allow you gimbal control via the joysticks.

To clarify, do you solely have the X5R with your Inspire or do you have an X3 camera as well?

It is a pain but you can find it under the DJI .Com .  Here is a link  to theX5 Raw page .  I have a suspiscion that you own the X3 as well.......

http://www.dji.com/zenmuse-x5r/info#downloads