Cannot connect to AWS Redis cluster over SSM session

RedisInsight (GUI for Redis)
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1

I have set up a Redis cluster in an AWS VPC and am able to connect through a SSM session

aws ssm start-session --target $bastion_instance_id --profile $profile \
    --document-name AWS-StartPortForwardingSessionToRemoteHost \
    --parameters host="$cluster_configuration_endpoint",portNumber="6379",localPortNumber="6380"

then

redis-cli -h 127.0.0.1 -p 6380 ping

When entering the same info over RedisInsight, I get a “Could not connect to 127.0.0.1:6380, please check the connection details.” error

What could be the issue? All network authorizations should be OK as the Redis CLI is able to connect to the cluster