Canon no longer supplies codecs for its raw files. Microsoft has finally updated its Raw Image Extension to include the codec for CR3 files for the 1DX Mark III. If you untick "Always show icons, never thumbnails" in File Explorer"s View>Options>Folder Options>View>Files and Folders in Windows 10, thumbnail images will now display. Raw Image Extension is available at no charge in the Microsoft Store. Search Raw Image Extension or Codec.