Pixhawk 4 sensors not found

This is my first build with Pixhawk 4. I want to show my drone battery percentage on my transmitter (FrSky X9 Lite). But when I click on discover sensors only RSSI and RxBt are found. (See image). I have connected my receiver (FrSky X9R) to the Pixhawk 4 via SBUS.

What did I do wrong?
Thank you in advance!