Wow thats kinda annoying, why couldnt they just be visible all the time? a storage crate doesnt go invisible when its not in use! Though im wondering why mine are visible out of build mode even empty >.>A trick you may be able to try is: Make sure you'r in creative and build mode. Place any block from creative mode into the storage block. This will instantly fill up all you're crates. It makes them allot easier to see while your placing them.
Good Luck