USB 3.0 flash drives not working on USB 3.0 ports

I have a recent iMac 5k and suddenly the USB 3.0 ports on the back are not recognizing any USB 3.0 flash drive.

In any of the 4 ports, the three USB 3.0 flash drives I have tried have not mounted and are not showing up in Disk Utility at all. Two USB 2 flash drives I have tried do mount in all of the ports. The three USB 3.0 flash drives also DO mount when plugged into a USB port on my wired keyboard.

Within bootcamped Windows 10 the USB 3.0 flash drives all work on the back ports as well.

The USB 3.0 flash drives do light up, but rather than lighting up initially and then lighting up during read/write, the light stays lit up when they are in any of the back ports.

I've done everything possible within Disk Utility on the flash drives and I've reset the SMC. I'm not sure what else I can try.

Any help would be greatly appreciated.