FWIW, I had to sprinkle crumbles on top of the FF too. They ignored the food for a day or two, then started gulping it down like they were starving. Now they eat about 2 troughs a day.
Okay, now my curiosity is peeked. Feed Store chicks are fed crumbles when they arrive. That might be why they reject the FF immediately and have to get used to it. I would be curious to find out if birds received directly from the mail would go straight for the FF, of if they would have an...