Pulled a working Nano/OPLM pair from another frame and installed in new Hex.
Rescued, erased, updated Nano, flight OPLM and ground OPLM to LP 15.09.
OPLM/Nano connected via Main port. Nano Main port enabled, 38400. Ground OPLM USB to laptop, speed set to 38400, no ports enabled (none connected). Signal strength for both radios at 100.
Flight radio set as coordinator. (Tried setting ground radio as coordinator but couldn't even get a signal, nada).
You can see from screenshots the radios are talking to each other. What stupid thing have I missed?