Groovy with copyfile restAPI to copy file from one instance to another fails

I am attempting to copy a file from the /Outbox folder (Data Exchange) of one Oracle PBCS instance to the /Inbox folder of another PBCS instance using the copyfile REST API.

This Groovy code has been functioning correctly for a long time, but it has recently stopped copying the file. The log file indicates that:

• The connection to the source instance is successful.
• The source file is found and validated.
• The file transfer itself does not occur.
• The process still records a success message and returns an HTTP status of 200.

The code in question is shown below:

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jsonResponse = operation.application.getConnection("restConn" )