Problems with Spektrum-Omnibusf4 set-up

[Artibill1]

Hi! Just starting out with drones - at a loose end during the Covid lockdown. Looking for some diagnostic help. I have either fried something or just being very stupid.

I have a set-up including an Omnibus f4 pro, Spektrum SPM4649T and a Spektrum DX6i, currently using Cleanflight.

I have flashed the Omnibus as instructed and get a relatively slow flashing blue led. The set-up binds correctly.

I have tried connecting the SPM4649T to either the SBUS/PPM-5V-GND pins, or to the J8 connector (DSM2-GND-3.3V), and have tried as many combinations in the ports tab, with the Receiver in the config tab set as Serial based (SPEKSAT...etc) and serial receiver set to SPEKTRUM1024 (although I have tried SPEKTRUM2048 as well).

In Clean flight I can get some activity out of the motors on the motors tab - so that part may be working.

What I need guidance on just now is that in the Receiver tab. I have a set of coloured bars for A, E, R, T, AUX1, AUX2, AUX3 - all centred at 1500 except T which is at 885. That looks good, but I cannot get any activity by moving the sticks on the DX6i.

What am I missing? Is there magic connection between DX6i and Omnibus that I have missed? Or have I cooked something?