Same temporary fix as last time - you will need to make sure that USB-C connection is secure.
Sometimes the opposite configuration works better with these USB-C ports. It is the same way with the charger on my old phone. If that does not work, then I would swap which of the four USB-A ports the cord is plugged into on the upper CPU. You could also try using a different USB-A to USB-C cable.
If that does not work, then you can purchase a replacement motion control board. I have sent you an invoice for one. That will definitely be a more long term fix - especially if the issue is a weak/broken UCB-C port.
I have sent you an email with the invoice and replacement instructions if that is needed.