For context: the target was invisible and near death. So we cast spike growth on the entrance with her in it and followed it up with a cordon of arrows. Basically target became visible and as it's next move it turned into an eagle which was inside of the later spell's range.
The spell's description states:
...whenever a creature other than you comes within 30 feet of the ammunition.
So would it only count the first time the enemy enters the range? Or would it also trigger if it was already inside of the trap and come closer?