I am under the impression that in "stereo" mode both green lights are supposed to be lit, indicating that RX audio is coming from both radios.
I am using N1MM+ Logger connected to a Flex 6600 transceiver, operating SO2R using full duplex mode.
Everything seems to work exactly like it did with my previous two K3 and YCCC box setup, except I seem to recall that in stereo mode both green lights would be lit. This gave me a visual indicator of whether I was using stereo mode or not.
I watched the OTRSP traffic being sent to the Flex virtual OTRSP controller, and indeed the correct message (RX1 transitions to RX2 for receive focus switch without stereo mode, and RX1S transitions to RX2S for receive focus switch when stereo mode is active). However on N1MM+ there is always only one green light showing. It is the same one that would be showing if stereo mode were turned off.
Any suggestions on how to debug this further? I am not sure where the problem lies. I do not have the YCCC box handy to perform a more thorough A/B test. I will read the OTRSP protocol spec more carefully but would appreciate advice on how to proceed.