I’ve tried to swap cables and osd’s I have 3 apm copters one works the other 2 do not display voltage or gps data until I connect my phone by bluetooth or usb. Then once the connection is made it starts “talking” and works fine.
Ive tried flashing all firmwares to 3.2.1 I don’t understand why I’ve beat my head on the bench time to ask for help.
Do you have both Tx and Rx connections in place between MinimOSD and APM/pixhawk on the 2 copters not working? If you only have APM Tx going to MinimOSD Rx (and no rx to tx) then you will have to set SR_ message frequency parameters to force APM to push out messages. Connecting USB would likely force this into effect