New
#11
@Lottiemansion - this is the location from which I originally downloaded iTunes, from Apple. This is a new install of Windows 10 with the latest version of iTunes. I was curious whether there really is a difference between the Windows Store version of iTunes and the one from Apple (in terms of drivers installed). I guess it doesn't matter, as I never got my download notification from the Store.
@Cr00zng - Agreed, iTunes shouldn't be required for viewing the phone as a storage device. I'm not sure how the above setting will help, but I'll double check it. My phone is always unlocked when I connect it, and I can connect it with the same cable to my Surface and it shows up in File Explorer without issue.
This worked before, on the same PC, before reinstalling Windows. I'm beginning to suspect a system driver issue. The mobo is about five years old, so the USB drivers installed by Windows are not the drivers issued by the manufacturer. It's a long shot, but maybe a more likely troubleshooting route than installing iTunes again.
I'll report back in about 12 hours, unless someone else has ideas. Thanks.