Macbook Pro Mail app opens .docx attachment into Pages with question mark boxes, but not iPhone?

Hello!

I'm having an issue where when I receive an email in mac Mail app that contains an attached .docx document, I'll double click the attachment which opens it in Pages and the formatting is all boxes w/ question marks.

I can select all the text and change the font to something else to reveal the contents.... Any ideas why this would be happening on my Macbook Pro Mail app but NOT my iphone?