Export confirmation page does not list fields

[btimby]

I am having trouble with this library. I was originally using django-import-export and it was working, however, I received timeouts during export so I decided to add this library. However, when doing so, I lost the list of fields on the export confirm page:

You can ignore the list of formats, I have set it to just CSV, so that part is working correctly. I did previously have the field list when using django-import-export. This is a very simple export, below is my resource definition and ModelAdmin:

class UserResource(CeleryModelResource):
    class Meta:
        model = User
        fields = [
            'username', 'first_name', 'last_name', 'is_superuser', 'is_staff',
            'is_active', 'is_handicapped', 'mobile', 'is_mobile_verified',
            'email', 'is_email_verified', 'tz',
        ]

...

@admin.register(User)
class UserAdmin(CeleryImportExportMixin, UserAdminBase):
....
    resource_classes = [UserResource]

Note that the export does work, and does include all the proper fields. It's just that this confirmation page is omitting the checkbox list of fields.