Primary site file uploads vanish, subdirectory subsites working fine

We’re tearing our hair out here. We have multisite configuration working, subdirectory style. File uploads work to the subsites, but the primary (blog 1) site doesn’t see any upload traffic. We’re running on Ubuntu so have the Debian style configuration layout.

/etc/wordpress/htaccess:

# BEGIN WordPress
RewriteEngine On
RewriteBase /
RewriteRule ^index\.php$ - [L]

# viewing attached files
RewriteRule ^/wp-uploads/(.*)$ /srv/www/wp-uploads/%{HTTP_HOST}/$1 [L]

# force HTTPS always
RewriteCond %{HTTPS} off
RewriteCond %{ENV:IS_HTTP} !1
RewriteRule ^ https://%{HTTP_HOST}%{REQUEST_URI} [R,L=301]

# uploaded files
RewriteRule ^([_0-9a-zA-Z-]+/)?files/(.+) wp-includes/ms-files.php?file=$2 [L]

# add a trailing slash to /wp-admin
RewriteRule ^([_0-9a-zA-Z-]+/)?wp-admin$ $1wp-admin/ [R=301,L]

RewriteCond %{REQUEST_FILENAME} -f [OR]
RewriteCond %{REQUEST_FILENAME} -d
RewriteRule ^ - [L]
RewriteRule  ^[_0-9a-zA-Z-]+/(wp-(content|admin|includes).*) $1 [L]
RewriteRule  ^[_0-9a-zA-Z-]+/(.*\.php)$ $1 [L]
RewriteRule . index.php [L]

/etc/wordpress/config-bclaconnect.ca.php:

table_prefix  = 'wp_';
$server = DB_HOST;
$loginsql = DB_USER;
$passsql = DB_PASSWORD;
$base = DB_NAME;
$upload_path = "/srv/www/wp-uploads/bclaconnect.ca";
$upload_url_path = "https://bclaconnect.ca/wp-uploads";

# Support for WP Networks functionality
define( 'MULTISITE', true );
define( 'SUBDOMAIN_INSTALL', false );
$base = '/';
define( 'DOMAIN_CURRENT_SITE', 'bclaconnect.ca' );
define( 'PATH_CURRENT_SITE', '/' );
define( 'SITE_ID_CURRENT_SITE', 1 );
define( 'BLOG_ID_CURRENT_SITE', 1 );

And finally, /etc/wordpress/wp-config.php:

define('ABSPATH', '/usr/share/wordpress/');
define('WP_ALLOW_MULTISITE', true);

There is no trace of the uploads in log files anywhere on the system. What on earth is going on? Anyone?

Frantic, in Vancouver,
Erik