Its the UV's. Modo's anisotropy is UV map based. You can fix this 2 ways:
#1 - Make a very tiny hole in your caps (top/bottom) of the cylinder, this will turn the triangles into quads. The hole method is what Lux used when they first demo'd this feature in Modo. Because it lets your UV map (quads) match your model (quads).
OR
#2 - Make sure your the verts at the center of the cap are at the top of the UV map, and make sure the verts at the edges are at the bottom of the UV map.
-TS-
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