So, I have two phones - Samsung Galaxy S7 Edge and Samsung Galaxy S7. Both are running Nougat. We use OTG cables and an SD card reader to view pictures on SD cards in the "field" through the QuickPic app (https://play.google.com/store/apps/details?id=com.alensw.PicFolder) . We've done this on Samsung S3s, S4s, & S5s (never had an S6) over the years. I've always plugged everything in, then when I was done viewing the photos, I unmounted the OTG/Card. All has worked effortlessly. Now, on my S7s I have a problem. Typically, I can always read the first card I use on the OTG, but usually if I attempt to read a second card the phone won't see the card. I've tried it with "unmounting" (through settings) and just unplugging the OTG - sometimes it works, sometimes it doesn't. I've tried different cards, different SD card readers, different OTG cables. Nothing consistently caused the problem. If I reboot the phone, most times I can read one card again - but typically not a second or third one. While I use the S7 Edge primarily, I've had the same problem with the S7 although sometimes it will let me read two cards before it quits. Any ideas?