The texture-less planets are a compatibility issue between the pack files and discovery data.
The texture files may be just fine, but if the data in the discovery files doesn't match that data in the texture files (for example planet size) - you get this.
Not sure how to fix it, though.
It is possible to remove the incompatible textures from the pack. Then Discovery will load the regular textures.
So Devil don't go pointing fingers at people's hardware.