x370 Killer SLI/ac Front USB doesn't work properly

It's been a while. The day after my last post, my mother died, so things got a bit busy around here, true story.

Anyway, I switched the mobo port the front-panel was connected to (the Asrock has two of them) and now both ports work, so it's probably an issue with the port on the mobo. In any case, I don't think there's any need to pursue further, since I now have a fully working front panel. That, and I have other things on my mind these days.

I appreciate the help guys.
Vandervecken

Note:

On the panel cables end that plugs into the MB. Is it polarized? Meaning the plug has one corner socket that is covered/blocked?

So you're suggesting the most likely problem is that both the original front panel and the replacement front panel suffer from the same defect? Isn't that pretty unlikely?

As I mentioned, I have already RMAed the front panel, and the new front panel has the same issue. The odds that both front panels are broken is very small.

The fact that one port works and one doesn't, when they both link to the mobo via the same connector, is really bizarre.

The Mobo has two USB 3.0 connectors, at the front edge of the board near the RAM.
The front-panel has one USB 3.0 cable that connects to one of those two connectors - either one. When connected, one of the USB *ports* in the *front panel* works, and the other one does not.
I'm not saying one of the USB 3.0 ports on the *motherboard* works and the other doesn't, I'm saying that on the front panel *itself*, one port works and one doesn't.