Title say it all. I tested this on a dedicated server and offline. I am using Minecraft Version 1.13.2, and mod version 1.83.1

just to make sure this isn't user error, I am placing the turtle above dirt and tilled soil (with an air block in between), and calling turtle.digDown(), and turtle.placeDown(). I have also placed the turtle on the ground and called turtle.dig(), and turtle.place() and observed the same result.