I connected a printer to both front ports and I was able to print. I have tried about 5 flash drives to the fron USB ports and Windows didn't detect any of them.
Sounds like USB power issue to the front ports. Printer does not require a +5VDC Tap to function, just the USB communication.
The USB Pinout:
Pin Name Cable color Description
1 VCC Red +5 VDC
2 D- White Data -
3 D+ Green Data +
4 GND Black Ground
Pin 1 ( 5VDC ) isn't strong enough at the front ports or open. Pins 2,3 and 4 ( D-, D+, and Ground ) allow for communication with printer successfully since printer doesnt need to be powered off USB Bus power.
I have seen issues with lower end computer cases and front usb port power due to too lite of gauge wiring used between the front ports and the connection with the motherboard. But still, thumb drives draw so little power to function that I'd suspect that pin 1 on your front ports must be missing the +5VDC to cause this. A powered USB hub would be a solution in which the thumb drives would be powered off of an external power source and not rely on the 5 volts from the front USB ports. Or ohm out pin 1 at the front panel to the connector that goes to your motherboard with digital multimeter
with computer off and power cord removed from power supply to avoid smoking anything.All pins should ohm out to less than 3 ohms each. If you find anything greater than 3 ohms, I'd inspect the wires for damage or corrosion. If no reading at all, then you have an open connection or your trying a continuity measurement against the wrong usb port pin and pin at the connector side. ( you might need a small/thin metal paperclip to stuff into the USB plug after removing it from the motherboards USB berg stick pins, otherwise sometimes the multimeter probe can make connection where the pin is locked into the connector and wire exits towards the front panel.
Also some cases have front USB ports with cables soldered directly to the USB port connectors and others have small circuit boards with a few capacitors on them for signal filtering etc. If you have a small circuit board you might find that the issue is a poor solder connection on it as for both ports would share the same +5VDC tap from the motherboard.