From my point of view Oracle Client issue.
What oracle Client is installed and what db version is being used? What is your cursor sharing db parameter set to? Have you had the DBA run a trace when this process was performed?
To be honest this is going to be more complicated in forum discussion
I would continue to work through the sr process.
Just a note that the XML import/export is only used for creating a new app, so monthly metadata changes will not be able to be imported via the XML import/export.
The correct way to perform this process would be to migrate the DB from the source enviornment to the Target and then use <Add Application>
You can then delete any data you do not need in the application by deleting the periods and re-adding them back.