Traefik 2 seems to concatenate multiple hostnames when requesting certs resulting in error

I am trying to configure a Traefik (v2.2.1) IngressRoute CRD resource as follows with the incubating traefik 2 chart (v8.6.1) in github at

          enabled: true
            enabled: true
            certResolver: production
                -  # canonical dns name for apps to use for prod environment
                -           # legacy dns name for prod environment, should be removed once apps updated

When I look at my traefik logs I see the following:

time="2020-06-21T02:16:35Z" level=info msg="Starting provider *acme.Provider {\"email\":\"\",\"caServer\":\"\",\"storage\":\"/data/acme.json\",\"keyType\":\"RSA4096\",\"dnsChallenge\":{\"provider\":\"route53\",\"delayBeforeCheck\":5000000000},\"ResolverName\":\"production\",\"store\":{},\"ChallengeStore\":{}}"
time="2020-06-21T02:16:35Z" level=info msg="Testing certificate renew..." providerName=production.acme
time="2020-06-21T02:16:37Z" level=error msg="Unable to obtain ACME certificate for domains \",\" : unable to generate a certificate for the domains []: acme: error: 400 :: POST :: :: urn:ietf:params:acme:error:rejectedIdentifier :: Error creating new order :: Cannot issue for \"\": Domain name contains an invalid character, url: " providerName=production.acme

Why is Traefik joining all domains.main and domains.sans hostnames with a space when requesting certs? Is this a bug in my chart configuration , the Helm chart used to install Traefik, or Traefik itself?

Many thanks in advance.