PX4 I2C Setup Assistance Required

Hi Guys

Been battling to get any of my I2C sensors to register on QGC.

Im using the pixhawk 4 with an airspeed PX4AIRSPEEDV1.1 and a level converter. tried on both I2CA and B with both attempts saying no sensor found. Swopped over wires SDA and SCL to check if comm wires were incorrect with no joy.
Also looking for more detailed manuals on the pixhawk 4 like plug pin outs any idea where i can download?

I have connected a power board PM07 and calibrated my voltage and current which work great.

Any ideas on what I am doing wrong?