Q: Can't attach document from icloud to gmail

I am trying to attach a Word file that is stored on my iCloud drive to a gmail message. My iCloud drive doesn't show up on the list of places I can choose to look for a document, e.g. there is Desktop, Macintosh HD, various folders, etc. How do I get my iCloud drive to show up in here?

I also sometimes get this issue when I am trying to save a file to my iCloud drive. When I click save as, the option for my iCloud drive doesn't show up.

Thanks