If you lift the top off the tank, you will see (should see) a plastic tube that is routed from the fill mechanism into the overflow tube, which is a vertical tube about 1" in diameter that goes nearly to the top of the tank. The plastic tube directs some tank filling water down the overflow tube, filling up the bowl. If that is disconnected or missing, there will be no water going into the bowl while the tank is filling, which would cause the symptom you describe. There are other possibilities, but this is the most likely.