Here's a little better news for Mac OS X Yosemite users who want to process their Leica M Monochrom (Typ 246) DNG files in either Apple's new Photos app or in their existing Aperture library. Apparently, even though importing B&W DNG files from Leica's new MM246 will create a small amount of havoc in your picture library, the damage isn't permanent, the library can be recovered and you won't lose or corrupt any previous pictures. Apple anticipates having a solution and will issue this in the next update to Photos. In the meantime, you could either wait to import your photos or use the recommended (and included) Adobe Lightroom software.
Here's the official statement from Leica:
Following further research and testing, Leica Camera would like to clarify the situation with the Leica Monochrom (Typ 246)’s DNG files and Apple’s imaging App’s in Mac OS X Yosemite 10.10.3 and 10.10.4. The problem is referring to the Photos app and Aperture.
Importing Monochrom (Typ 246) files into a Photos or Aperture library will cause the library to repeatedly quit unexpectedly on launch, and Leica Camera does not recommend using the Apple ‘Photos‘ App for DNG files from the new Monochrom (Typ 246) until this issue is addressed. However, importing these files does not cause any data or image files to be lost in an existing Photos library.
Leica and Apple are collaborating to resolve this issue and develop a solution so that the DNG files from the new Monochrom can be used with the Photos app without any issues in the near future. It is anticipated that Apple will have this resolved in the next update for Photos. Libraries that experience this issue will be recoverable when the issue is resolved. The user can also revert to a backup of their library made before importing the Monochrom (Typ 246) files.
Meanwhile, Leica Camera recommends that all users of the new Leica Monochrom to use Adobe Photoshop Lightroom CC/6 for DNG files of the new Monochrom. The latest version of Adobe Photoshop is fully compatible with Mac and Windows PC. The JPEG files from the new Leica Monochrom work with all Apple applications.
Leica Camera Inc. will include a ‘Warning Notice‘ regarding the Leica Monochrom (Typ 246)’s incompatibility with Apple’s Photos app in all the new Monochrom product boxes (catalog #10930).