Importing a folder of zips doesn't work. Directly importing does

If I try and import a folder of zip files, I get unreadable file errors. If I directly import the zip files individually they work.

Here’s an example output:

$ beet import test\ import/
unreadable file: /nas/music/test import/Abby Echiverri vs. The Lone Flanger - Showdown At Proxima Centauri -
unreadable file: /nas/music/test import/arovane -
unreadable file: /nas/music/test import/DJ Guy - Structures + Rhythms '94-'
unreadable file: /nas/music/test import/Dr. Sync - Acid
No files imported from /nas/music/test import

And the output of beet version:

beets version 1.4.9
Python version 3.7.3
plugins: convert, discogs, edit, embedart, fetchart, fromfilename, ftintitle, hook, importadded, lastgenre, plexupdate