How to resolve this problem
Stair stepping means there's not space for the inflation layer in the volume. By default the mesher will first compress the inflation, if that fails (ie the inflation is still too thick) it'll remove layers of mesh. It's a warning rather than an error, so look at the mesh quality (cell quality and resolution) and decide if it's a problem. When you do look at the mesh you can also judge whether it's suitable for your needs.
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