Creating custom icons for OdySupportIcons

[casusfere]

Hi all! I'm trying to create a pack of custom icons to use with OdySupportIcons, and I'm floundering a bit. Can anyone share the guidelines for the icon files?

I know that the images dimensions need to be a power of 2, so my files are 64x64, and i know the file type is .dds.

However, only some of my icons are actually showing. Of six icons I've tried to add, only three actually show. The others just show as empty space. I don't think I've done anything differently between the files, but I'm not sure what the actual file requirements are. Should my files use mipmaps? Is there a specific format of .dds I should be using? I'm creating the files in GiMP.