What do you mean by “little to no reaction”? If there is
any trace of blue or black, then there is still unchanged starch present. You should be looking for no colour at all - just the yellow of the iodine itself. It is wise to test half a dozen or so apples with different skin colours and from different parts of the tree before making a decision. Also, if you are using a dropper, spot the iodine at different points on each cut fruit from core to skin.
I haven’t checked my Dabinetts but in South Oxon my Harry Masters and Kingston Blacks are still clearly unripe, despite having all dropped to the ground.
Andrew