A notification appeared across the top of my Mac app today asking me to update. I clicked the link and the App Store opened, showing me my Mac app was up to date! When I compared version numbers, I found that I had 6.61, not 6.71. I couldn't update there, so I went to the Evernote web site and downloaded the updated app there. When I launched again, I had the correct, updated version, but the app recognized an App Store version and had to copy all my notes to a new folder and then update them.
Any clue as to why the App Store wasn't cooperating with the update?