Nice explanation for the iOS 7 issues from John Wallrodt:
FileMaker To and iOS7 Bug
by John Wallrodt
September 16, 2013
According to FileMaker there is an issue between iOS 7 (due to be released on Sept 18) and FileMaker Go that affects the creation of a unique UUID number, which has the potential to wreak havoc on databases that rely on that unique number for syncing. This bug hits our own databases, as well as the copy of the database that is hosted at this blog.
Syncing from multiple copies of a database requires that each record have a very unique number. This is more than a straight serial number, since two separate copies of the database can each create a record in the same table which would give them the same serial number. Instead, our database relies on something more specific, a UUID which is generated from several types of information.
The UUID that we use is a custom function written by Jereme Bante a few years ago named UUID.New. It creates a unique number for each record based on:
more... FileMaker Go and iOS 7 Bug | Paperless Archaeology.