Question / Problem:
On occasion exported documents disappears.
Answer / Solution:
In most cases the customer has two Online Connect running. Often some old test server where they forgot to remove the Online Connect service.
These two Online Connect services will then compete in exporting the files. Quite often the image files goes to one server and the XML to another.
What to do
Find the other Online Connect and stop it.
If you check the document history for the documents that went missing, you will see exactly where they were exported and to what server.
Go to that server, stop and uninstall the Online connect service.