Hi there,
my Alfie was the same -up until he turned around 1 year-old, he used to eat and finish off his bowl of dry food (Wainwrights) in seconds. Then suddenly he decided that he didn't like it. I was initially worried because he went from being a greedy, eat absolutely anything, dog to one that refused to touch his food. I then went out and bought him some Wainwrights wet food/meat and he ate that straight away. I now just keep him on the wet food as he no longer wishes to eat dry. I did try a couple of other brands of dry food but no, he won't touch it. You could perhaps try introducing a different brand of dry to Nala's current food to see if it's the brand that she doesn't like, or maybe you could try mixing wet food and dry food together?
Josie x