Evening; 
looking for some assistance.

Radio: FrSky Taranis Q7 [Access]
Receiver: FrSky M+
Fc: Mamba 722

Desired end state - run F.port from the M+ to the FC.

1. I've updated my tx firmware to this [2021-02-03 ISRM  v2.1.6]
2. I've updated the Rx firmware to this: [Archer-X_2.1.7.frsk] - this would not update via OTA - when attempting to do this by OTA the system hung at 'waiting for RX' [despite cycling the RC power] - the FW was updated by s.port plugged into the radio and indicated successful.
3. The receiver is bound to the transmitter - however when I select the receiver and 'options' within the tx setup page - it hangs at 'waiting for RX'

I have had the 'waiting for RX' issue on a previous build and instead opted for an SBUS connection but I would like to understand what I'm doing wrong here.
I think i need to select F.Port under options to enable this (hence why the below set up in betaflight isn't working (?) )

the UART for S.Port / F.Port on the Mamba 722 seems to be UART 5.
In beta flight I have set UART 5 to "serial RX" and in the config tab I've set up "serial receiver" and FRSKY, F.Port as the options.

Any thoughts or experience with this would be appreciated.

cheers.

Have you tried updating OpenTX

ok updated to openTX 2.3.11 - solved, thanks.

Great