Left rail on old switch charging but not connecting joycon

Hi all, I hope I found the right place to help me

My left joy con rail is charging but not connecting the joy con in hand held mode, I’ve tried replacing the rail with a known good rail, and tested it old rail on a known good switch (with no issues) I’ve tried pairing a known good joy con with same issues

I’ve also tried cleaning the ribbon cable connection on the mb as was as a factory rest, I’m stumped on what is coursing the issue, please let me know your ideas