changing charm's subnet-id does not seem to take effect

I deployed k8s 1.23 on openstack focal-ussuri without setting the floating-network-id or subnet-id values. After deployment of the charm/bundle, I updated the config with:

# Set to floating-ip/external subnet
juju config openstack-integrator subnet-id=2d5fc65b-4b58-4613-a3b8-3eda93e22c07
# Set to floating-ip/external network
juju config openstack-integrator floating-network-id=6b911c79-816a-4c24-aff2-59edf648699e

Then, I tried to create a k8s service of type LoadBalancer and received the following error in the service description:

Error syncing load balancer: failed to ensure load balancer: error creating LB floatingip: Resource not found: {"NeutronError": {"type": "ExternalGatewayForFloatingIPNotFound", "message": "External network 6b911c79-816a-4c24-aff2-59edf648699e is not reachable from subnet 2d5fc65b-4b58-4613-a3b8-3eda93e22c07. Therefore, cannot associate Port 17307d04-918d-481c-acba-42c6c35db52c with a Floating IP.", "detail": ""}}

So to rectify the situation, I tried to update the charm's config again with:

# Set to tenant subnet
juju config openstack-integrator subnet-id=b3f182e6-e7a1-46d4-b738-0cac65e8db99

Then, I tried to create the k8s service of type LoadBalancer again and received the following error in the service description again:

Error syncing load balancer: failed to ensure load balancer: error creating LB floatingip: Resource not found: {"NeutronError": {"type": "ExternalGatewayForFloatingIPNotFound", "message": "External network 6b911c79-816a-4c24-aff2-59edf648699e is not reachable from subnet 2d5fc65b-4b58-4613-a3b8-3eda93e22c07. Therefore, cannot associate Port 17307d04-918d-481c-acba-42c6c35db52c with a Floating IP.", "detail": ""}}

So it looks like changing the charm's subnet-id/floating-network-id config option don't always work successfully. I tried to also remove-unit/add-unit to get around this but was only able to update the floating-network-id this way but the subnet-id always remained as "2d5fc65b-4b58-4613-a3b8-3eda93e22c07".

I was able to solve my problem by redeploying my bundle and having the floating-network-id and subnet-id preconfigured to the desired values but the charm should be able to update on demand.