This is a relatively minor issue compared to everything that's been happening, but it's been going on for years through every different update, and I wonder if there's any solution. Usually, if I upload new photos from my camera into the computer, GS will not be able to access them unless I close and restart GS. Also, frequently, if I am working for quite a while, even without new photos, I will lose the ability to see the photos in GS. They all start to appear as "?". Or it will all be blank, and at the bottom of the screen it says 0 Images. The "refresh" button does nothing. I have seen it work sometimes before, but usually nothing. I have a mid 2012 MacBook Pro running Sierra 10.12.6. Any ideas?