Using a CS18 with an RM that's in an AVB stagebox/monitor mixer configuration with a StudioLive AI Console is not a currently supported configuration.
When a CS18 connects to an RM mixer, it triggers the RM mixer to attempt to reconfigure its AVB connections in order to send and receive audio between the CS18 and RM. This in turn can interfere with the AVB connections between the RM mixer and the AI Console, causing loss of audio between the RM stagebox and the AI mixer at FOH position.