For those still having issues - this process works for me every time when using the Radio Panel since SU5:
- Assign a keyboard shortcut to the AVIONICS MASTER 1&2 ON if you’ve not already done so
- Once you’ve loaded into the main menu of MSFS, open the windows task manager and check that the Logitech MSFS plugin (LogiMicrosoftFlightSimulator) is running. If not (which it normally isn’t for me), manually run the plugin. I use the shortcut it created when I installed it, but if you no longer have that shortcut, then it runs the following:
"<LOCATION OF PLUGIN>\LogiMicrosoftFlightSimulator.exe" --run --force - Load up a flight, turn batteries and ground power on, then press the avionics keybind (in airliners). The panel should light up and work correctly.
- If this still doesn’t work, try closing existing copies of the plugin in the task manager, then repeat step 2 again. Once you’ve done that you’ll need to go back to the sim, click ESC and restart the flight, then repeat step 3
Hope that helps!