Can't login under Multisite subsites (redirect issue?)

We have our WordPress Multisite setup in the root folder at:
https://blogs.domain.com/

All network sites are in the format
https://blogs.domain.com/test-site/

If you try to sign in to Test Site at: https://blogs.domain.com/test-site/wp-admin or https://blogs.domain.com/test-site/wp-login.php Neither will work, the screen just shakes.

If, instead, you sign in at https://blogs.domain.com/wp-login.php You can access your sub site just fine.

Here’s our Multisite .htaccess:

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

# 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]

Here’s our relevant part of wp-config.php:

/**
 * For developers: WordPress debugging mode.
 *
 * Change this to true to enable the display of notices during development.
 * It is strongly recommended that plugin and theme developers use WP_DEBUG
 * in their development environments.
 */
define('WP_DEBUG', false);
/* Multisite */
define('WP_ALLOW_MULTISITE', true);
define('MULTISITE', true);
define('SUBDOMAIN_INSTALL', false);
define('DOMAIN_CURRENT_SITE', 'blogs.domain.com');
define('PATH_CURRENT_SITE', '/');
define('SITE_ID_CURRENT_SITE', 1);
define('BLOG_ID_CURRENT_SITE', 1);

/* That's all, stop editing! Happy blogging. */

Any idea what we have wrong?

Thanks!