Failing TLS handshake between OpenTelemetry and ElasticSearch using ES CA Cert

I downloaded the CA cert for Elastic Search from the security page. I ran the command curl -v --cacert "ESCert.crt" "myESEndpoint" and verified connection just fine.

When I configure my OpenTelemetry collector config:

exporters:
logging:
verbosity: detailed
otlp/elastic:
endpoint: myESEndpoint
headers:
Authorization: secretToken
tls:
insecure: false
ca_file: "myESCert.crt"

I'm getting this error:

"rpc error: code = Unavailable desc = connection error: desc = "transport: authentication handshake failed: x509: certificate signed by unknown authority""

I'm not sure why curl would work but not the connection from the collector to ES. Any ideas?