I am going overseas so I have been testing out for my wireless passport to down load Go Pro photos via SD card adapter this week. But I cannot see thumbnails on my iPad. I have reboot and reset drive but to nail avail. GoPro pics are jpeg. Do I need to flick a setting??
For MPW, try connecting your MPW to the power adapter and check again. The MPW only generates thumbnail when it is connected to a power source as this task drains battery fast.
You may also need to hit the rebuild button in the device UI to trigger the indexer to generate the thumbnail.