USB-C Charging issues

In my line of work, which involves repairing phones and tablets, I've recently encountered a recurring issue with the newer series of devices. It seems that when the charging cable is inserted one way, the device charges as expected, but when you flip the connector over, it either doesn't charge at all or charges very slowly. This is a bit unusual because typically, such issues are related to the charging port or the assembly itself. To troubleshoot, I've tried various charging ports, but they all exhibit the same problem. I've also experimented with different sub flex cables, but the issue persists. I'm curious if anyone else in the field has come across this problem and if there's a solution. My suspicion is that it might be a faulty PMIC (Power Management Integrated Circuit), but I would expect the charging lines to converge before reaching the IC, meaning that if it were the PMIC, it should charge properly regardless of the connector's orientation.

Any help is greatly appreciated.

Thanks in advance.