Hi,
I'm working on a project where I want to control a drone from serial and not from a radio transmitter. I have a working setup and configured betaflight properly (I think) where I have defined the receiver opinion in the configuration menu as "MPS RX input (control via MSP port)".

It is working fine and I'm able to communicate with the flight controller using Multiwii Serial Protocol (I'm using this one). My issue is that I keep getting the arming flag "RXLOSS", which according to this indicates that "No valid receiver signal is detected". It is correct. There is a signal being sent. But that is exactly the setup I want!

So, how can I disable this RX LOSS arming flag?

Arming is a serious safety feature and there might be additional checks to ensure a quad doesn’t arm without a valid receiver signal.

You might need to chase pull requests such as this to disable the safety features in Betaflight: https://github.com/betaflight/betaflight/pull/9040

Else your best bet is chatting to the decs at the Betaflight Slack channel.