i would bet it's because you haven't specifically included a separate 16x16 version of your icon within itself so it's using a default 16x16 which is, apparently, the pyramid.
try including atleast a 32x32 version and a 16x16 version in your icon when you create it. attached is a single icon with 3 different-sized versions. 32x32, 24x24 and 16x16. save it somewhere and right-click "preview" and then zoom in and out and you'll see that windows dynamically chooses an "appropriate" version of the icon.
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