Ok, I purchased a standard USB 3.0 micro to USB adapter (looks exactly like the one that somebody posted above that he says is working), and it did not work. It would not beep or do anything when I plugged in any flash drive. I just picked up this OTG cable from Ebay, and it works, just like the white one that another poster bought on Amazon. Every flash drive I plug in does not work. Most of them do, and one of the says it is not recognized, but works perfectly. There could be a delay of 10 to 15 seconds before the drive pops up, especially for a larger drive. The ones that do not work either show the drive, but I get an error when I open it, or it says it cannot recognize it and it does not hsow up in File Explorer, though I can click to safely remove it. So I do not believe we have a hardware issue. The fact that several of my drives do not work could mean there is a driver issue, though I have often heard of issues from techs I support who have problems with flash drives, and formatting them with the HP Flash utility fixes them, so I may try that with the drives I have issues with. I do note that this cable connection at the 2520 seems to be a little looser than the adapter I bought. but that does not seem to be an issue. I am just glad I do not feel I have a hardware issue on the USB port and do not have to worry about returning it since otherwise it has been perfect.
Micro USB 3 0 9pin OTG Host Flash Disk Cable for Galaxy NOTE3 N9000 Black 9 Inch | eBay