Computer doesn't recognize drives (phone, ereader) plugged in via USB

I have a new computer I built, and it doesn't recognize my phone or my ereader. It charges them, but that's it. On my old machine they'd show up as drives and I could transfer files, etc. with either device (a Nexus 6P and a Kobo Glo reader), but on this machine, the charging is all they will do when connected via USB.

How do I get the computer to realize they are there so I can transfer files and things? I have tried removing the USB drivers from the Device Manager and reinstalling them, no change. I have tried every USB port on the computer to see if it was just one bad port, no change.

It recognizes and interacts fine with my wired xbox360 controller and my webcam, using the same ports I am trying to use for the phone/ereader data transfer.

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