Hi

The Windows 8 Photos App (= Modern UI one) does not support installed WIC codecs, whereas the Windows Photos Viewer (= Desktop UI one) does.

How to reproduce:

1. Install Windows 8 Pro RTM.
2. Install a WIC codec e.g. Adobe's DNG Codec (or Ardfry's or FastPictureViewer's one).
   
3. Try to open a vanilla DNG file with the Desktop-UI "Windows Photos Viewer": the file decodes successfully.
4. Try to open a vanilla DNG file with the Metro-UI "Windows 8 Photos App": nothing is displayed, failure.

Just wondering whether it's a weird bug or some expected "feature" (or lack thereof)...

N.B. Please spare me the usual useless/nonsense remarks such as "did you reboot" or "disable your firewall" :D

Got confirmation from a third-party WIC software developer (whereas MS staff was clueless...).

More or less, Microsoft considers that 3rd-party WIC codecs are not an issue for the Desktop UI and its desktop apps, yet third-party are not welcome to compensate for obvious, dramatic deficiencies of the modern UI. This way, MS proudly retains full control and ownership over their feature-poor, half-functional Modern UI *grin*

So... basically, any and all WIC codecs for formats unknown to/not developed by Microsoft are forbidden in the Modern UI apps. Another good reason to stay away from this "Useless Interface" :)