Embedded Excel workbook differs from original, appearing empty when opened

[stevencohn]

1. Create a Word or PowerPoint file
2. Embed an Excel workbook, can be either .xls or .xlsx
3. Open with viewer and let it export embeddings
4. Open the exported Excel
5. Excel app opens but its window is blank, implying that it cannot read any sheets from the workbook

I've tried this on my own separately and found the only way to export with fidelity to original is to use OLE automation, open the workbook in a new instance of Excel, invoke a Save operation, and then close the instance.

Is there a better way?