Getting E_ADEPT_DOCUMENT_TYPE_UNKNOWN when trying to load an .ascm file

I've downloaded the .ascm three separate times, and get the same error each time I attempt to use the file with Adobe Digital Editions.

This only occurs with a specific eBook. I've tried 7 other eBooks, and those other eBooks are added successfully.

Full error:
Unable to download

Error getting License. License Server Communication Problem:

E_ADEPT_DOCUMENT_TYPE_UNKNOWN

Steps to reproduce:

Purchase "George R. R. Martin's A Game of Thrones 5-Book Boxed Set (Song of Ice and Fire Series)" from Google Play Books

Download as EPUB
Add .ascm for EPUB to ADE

Troubleshooting attempted:
Downloaded .ascm again

Asked Google for assistance - they suggested the following:

• Redownload eBook
• Reinstall ADE
• Install Adobe Acrobat
• Re-authorize ADE
• Try again