just tried out a USB 3 cable on the 2.4Amp socket on this battery pack to see if that made it work. it did not. unplugged it, went to plug in the same cable in the 2.1 amp, couldn't get it in, got annoyed , used a different cable. I've now gone to plug this USB 3 cable back in the wall socket it came from and it did not fit. no matter what. I investigated, found a chunk of plastic jammed in the plug. wondered where it was from...

...turns out it's from the 2.4A socket in the battery pack. :|