I'm assuming we're talking about gouging the stone....digging the edge into the stone. If not, please disregard the following.
1. The stone is flat
If assumption is correct:
You're doing something wrong.
You should be flattening after each use anyway....regardless of gouging the stone. It's a good practice.
You are grinding the tip at too steep of an angle. It's the only way you can be gouging the stone.
It's a common mistake....having to move one's hand/wrist to account for the curve of the tip is one of the most difficult things to learn.
Use the Permanent Marker trick to see if I'm correct or not. Mark the edge and sharpen like normal. If the marker is only removed at the very edge, I'm likely correct.