Error - io:job could not be initialized: missing field accessing 'heartbeat.monitors.0.hosts.0' (source:'/etc/heartbeat.yml') - elk

Question

Heartbeat configuration file is below
# Directory + glob pattern to search for configuration files
path: ${path.config}/monitors.d/*.yml
# If enabled, heartbeat will periodically check the config.monitors path for changes
reload.enabled: true
# How often to check for changes
reload.period: 10s
heartbeat.monitors:
- type: http
id: my_app
name: "Check my_app liveness endpoint"
labels.application.name: my_app
schedule: '#every 1m'
service.name: 'my_app' # must be same as in apm
hosts: ["https://${host}/path/to/destination1", "https://${host}/path/to/destination2"]
check.request.method: HEAD
check.response.status: [200]
fields_under_root: true
fields:
service.environment: "${my_env}"
labels.application.name: my_app
####Enabling logging to heartbeat###
logging.level: debug
logging.to_files: true
logging.files.path: /usr/share/heartbeat/logs
logging.files.name: heartbeat-log
logging.files.keepfiles: 30
logging.files.permissions: 0640
output.kafka:
hosts: ["${KAFKA_URL}"]
ssl.verification_mode: "none"
topic: "heartbeat"
partition.round_robin:
reachable_only: true
client_id: ${MY_APPLICATION}-heartbeat-${MY_ENVIRONMENT}
required_acks: 1
monitoring:
enabled: false
this configuration is deployed as a Configmap inside the heartbeat pod.
But after the deployment, we are getting this error in Kibana Uptime Monitor :
Also tried hardcoded the variables which are there inside the yaml posted. The result is the same.
Can anybody help me?