Ixpand usb 3.0 not working with Iphone 7

in setting do you have icloud photo library turned on? If so that could be the issue. Some of the images may not be stored on the phone itself and there could be something going on in the download process that is causing the issue. If icloud photo library is turned on try turning it off and see if you can transfer only the files that are stored locally on the phone.