I have a yes/no column with a default value of No. This column is defined at the site collection level and is first included in a content type which is the parent content type of several others. These children content types are all added to a document library. There is a default content type defined on the list.
For almost all of the items uploaded to this document library, the default value for the column is set. Recently, I had four failures for it to be set. For these four documents, the column was set to (blank).
The end user does not have the ability to set it himself (it is created as part of a document imaging workflow). I cannot replicate the issue myself. It happens so rarely (four times out of about 6200 items) that I'm not sure how it happened at all.
Is there a way to further reinforce this default value being set? How do I go about diagnosing exactly where this blank came from? Is it even possible for a yes/no column to be set as not yes or not no?