This should be self-explanatory. It's as if MEP scrambles its information about the clip thumbnails. Once it happens, my tests appear to show that it's permanent. IOW, re-opening the project (in MEP 2014 or 2013, and probably all other versions) doesn't fix it.
Not reproducible to order, of course, but I get the problem frequently. Anyone else ever see this?

Or for better quality: https://dl.dropboxusercontent.com/u/4019461/MEP-ClipMismatch.jpg
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Terry, East Grinstead, UK