Before changing any links I plugged in a sbus receiver, enable uart3 as Serial RX in ports, selected SBUS receiver and set serialrx_provider as SBUS.
It did not work either
Removed SBUS 0R link (leaving the PPM one in place), back to the PPM receiver and still not work either BUT after trying various options I got it working with these settings
YES, No Receiver !!!
Sticks bottom right
Sticks top left
Changes to TX sticks needed to get correct channel movements
Although this worked I'll not be trusting it in flight.
The forums do talk about some workarounds which I'll try later.
"(0) Full erase flash latest FC firmware (1) Connect, goto configuration tab, select RX_SERIAL, save and reboot. (2) Connect, goto ports tab, turn on SerialRX on UART3, save and reboot Sounds like Serial RX configuration, right? (3) Connect, goto configuration tab, verify RX_PPM has revived. (4) Goto receiver tab and see your PPM receiver working!!!"
There appears to be a later version of iNav,1.8.0 which I'll try. The release notes show changes to receiver configuration and selecting so maybe this has been resolved.
Need to leave it now, will carry on in the morning