Usually this is the OrderReferance ID column in the Orders table.
The string looks like the session ID.
Double check that the OrderReferenceID column is set to text in the DB.
then in the Store order Summary server behavior, make sure the data type for the order reference ID column is set to text as well.
If you still have a problem, double check in the Store Order Summary server behaviors and the Store order detail server behaviors for any column you are storing the session ID in.