In th screenshot I have attached there are two images selected in Bibble (like a stack) and you can see that an adjustment is visible in the "Basic Adjustments" tab [?]
These images (at least one of them) has a 0.57 negative exposure adjustment. However, they are both without the "edited" or Paintbrush icon.
I have come to the conclusion that either I am confused about what the paintbrush means, that there is some setting to control it or for some reason the changes for these NEF files aren't displaying.