This error is actually on the Amazon side for what we can tell. It happens occasionally when the Amazon API fails to properly convert the Launch Date on their end.

We've confirmed with their developer support that the proper date format via API is: "2014-09-23T08:39:36.000Z" to the API which is then converted into their required format.

It almost always converts to the required format, but on a few occasions it has not converted and the only resolution we have found is to change the value in Amazon or to Delete and Re-add the items (most effectively done by bulk exporting all the product details, deleting all, and adding them again.