When the PDF was inserted in the container field, was the store by reference option selected?
Is this PDF stored in the correct folder for web publishing?
Have you moved or renamed the file after it was inserted?
You can check the contents of your container field by defining a calculation field to return text and simply placing the name of your container field in the specify cacluation dialog. Make this field several lines high and you can check it's file path (if stored by reference) to see where the container field is "pointed".
Thanks for response. None of the missing contents was put in the co ntainer fields by reference.
Hopefully, you have multiple backups going back in time. I'd use filemaker pro to open each of these back up copies to see if any show the container field contents. That may give you a clue as to how this happened.