Only thumbnails viewing from cr2 files

[Lincoln]

In this case it was cr2 files from a Canon EOS-M when downloaded and indexed into the database only showed the preview jpg file. I opened the files in the Canon Digital Photo Professional software. Then noticed that the colour space was showing as sRGB whereas I had set it to Adobe RGB in the camera. Selected all the images - changed the metadata in colour space to Adobe RGB and saved the files. Problem solved.

[Mario]

This problem was apparently caused by the installed WIC codec which was unable to process the original files properly. After 'correcting' the files, the WIC codec could handle them and in turn IMatch was able to import them.