Post any defects you find in the released or beta versions of the ImageMagick software here. Include the ImageMagick version, OS, and any command-line required to reproduce the problem. Got a patch for a bug? Post it here.
There seems to be a bug when converting from png to ico format, the solid colors in the png become fully transparent but the shadows and such seem to be converted as normal.
I hope it is possible to fix
(I tested both standars size 32x32 and larger 128x128 with the same result.)
perhaps you could provide an example of where it is failing and identify what version of IM. If your IM is old, perhaps try upgrading and see if it fails with the latest version.