Losing metadata fields in document when copying document from one library to another

I have a document that incorporates SharePoint metadata within the document to provide dynamically updated data depending the change in SharePoint. The document properties populate perfectly fine in the source library, however when copying the document over into a new library using Nintex copy action, certain properties lose their associated metadata. See below: 

Source library document: 

Copy of Document in Destination Library:

What’s strange is that the metadata is not actually lost. It is still present when I view the document properties… however the association between that document property and the field within the document is lost, as can be seen below and above with the document copy.

Document property on copy in destination library

Any insight would be greatly appreciated.