Just a cautionary note to avoid my mistake. I make sure that I'm always using the latest version of software / firmware in all my devices and Jeti is no exception. I set up my PB Royal using Jeti V3.24 UDI 16 which gave me 16 channels at the PB.
Jeti then released v3.25 and so I updated my Rxs. I then discovered that I can only access 12 channels at the PB although I can see 24 channels at the Tx. So, with the help of the excellent Jeti Forum, the following was pointed out to me:
"V3.25 adds 24 channel support via EX Bus but does not support UDI16, just UDI12. You need to update your Rsat2 with V3.24 UDI16 firmware"
So, if you are experiencing this issue you might want to check your Jeti firmware version.