My personal account blah@example.com became part of a Google Apps business account that used the same email address. After some problem that required intervention by Google help desk people, I transferred the history to the new entity.
Not sure if the above has any bearing on the AdWords Editor issue, but it doesn't see the ad groups in most of the campaigns it imported, particularly the active ones. They are all there when I log directly into AdWords.
As an aside, I checked out the Google Group for AdWords and found it swimming in spam.
