Help with Cubepilot Orange and Radiolink R12DS no throttle signal

I’m new and need a little help.
I’m using cube pilot orange with radiolink AT10II and R12DS with readytosky 30A opto esc and Qwinout 5010-750KV motors. The receiver is in SBUS mode and connected to RCIN on the cube. I was able to do the radio calibration but when I connected the ESC the motors, the motors keep beeping and my online research pointed me to a loss of throttle signal.
When just using the battery with external UBEC and a motor connected to ch3 I can use the throttle.
As a newbie I’m wondering what i have missed.
Any help would be greatly appreciated