Master-Slave Config ‘Not-Connected’

Hi,
I’m using a Master-Slave configuration but I’m not able to get the plugin to connect.
When I define the WP_REMOTE_HOST per server individually, to either the master or slave it works. However, not when I define them in master-slave config as mentioned in the documentation.

The table shows Master & Slave in the server list however it says no password for each server.

The diagnostics shows:

Status: Not Connected
Client: PhpRedis (v4.3.0)
Drop-in: Valid
Connection Exception: Connection refused (RedisException)
Redis Extension: 4.3.0
Predis Client: 1.1.1
PHP Version: 7.2.19

Connection refused. Which tells me that the define password isn’t working. It does for single host however.

wp-config.php has the following:

define( 'WP_REDIS_SERVERS', [
        'tcp://1.1.1.1:6379?database=0&alias=master',
        'tcp://1.2.1.1:6379?database=0&alias=slave',
        ] );
define( 'WP_REDIS_PASSWORD','password123');
define('WP_CACHE', true);

How do I define a password for both master and slave? The password is the same for password and slave so I’ve assumed a single declaration will work?
Thank you in advance Till!