I’ve searched to no avail on this subject. I’m using a 2017 12.9” IPad Pro 512gb and the Apple SD card to lightning adapter. I’ve had this issue with every version of iOS 11. Currently running iOS 11.1. I’m shooting raw images with a Nikon d750 on San disk extreme pro 95mb/sec card. When I go to import them onto my IPad it’s fairly quick, but then I click the thumbnails and they are pixilated and don’t buffer to full resolution. Some times I have to wait a full day before they are full res. Has anyone else experienced this issue?