If you transfer the files to the iXpand they will be stored on the iXpand. You will not be able to open the pictures in the iXpand app but if you transfer the pictures to the iXpand they will be saved there.
Where are you trying to transfer the pictures from? iOS has a limitation that only allows third party apps access to the camera roll so if the pictures are on an iOS device and not in the camera roll the iXpand app may not have access to them to transfer them to the iXpand drive.
