What we have is a situation specific to ExportPDF.
No Acrobat (the desktop application) involvement.
My guess is that how the PDF was created has bearing on ExportPDF's processing.
Will Adobe ExportPDF convert both text and formatting information?
Adobe ExportPDF is capable of exporting high quality information, but the quality of your Word document depends on the quality of the PDF file you start with. For instance, if your PDF file was originally authored in Microsoft Word and converted to PDF using the PDFMaker functionality of Adobe Acrobat®, your PDF file contains a rich set of information that can be captured by Adobe ExportPDF. This includes relative positioning of tables, images, and even multi-column text, as well as page, paragraph, and font attributes.