Tiptoe walking or "toe walking" is a sign of a child's inability to transfer their weight from the heel to the toe. (We would call it a typical heel-to-toe walk.)
It's natural to want to force the heel to the ground using casts or shoe inserts to create a typical heel-to-toe walk.
But as I always say, "With force, you get force, and with rotation you get movement."
A number of things can interrupt a child's ability to weight transfer through the foot.
Things that could cause toe walking are:
What's more important than the causes of toe walking is for you to note that your child has an inability to weight transfer through the foot.
The transitional skill that is lost here is the child's or person's ability to start with flat feet, go up on their tiptoes, and then bring the heels back down to the...