Traefik LetsEncrypt throwing an error: DNS name does not have enough labels, url

Traefik LetsEncrypt throwing an error: DNS name does not have enough labels, url

I'm using HomelabOs, and Traefik v 1.7.10.
My Traefik Toml looks like this:
debug = false

logLevel = "ERROR"
defaultEntryPoints = ["http", "https"]

[entryPoints]
  [entryPoints.http]
  address = ":80"
  [entryPoints.https]
  address = ":443"
  [entryPoints.https.tls]

[retry]

[api]

[Docker]
  endpoint = "unix:///var/run/docker.sock"
  domain = "pinguinshow.com"
  watch = true
  exposedByDefault = false

[acme]
  email = "foo@myemail.com"
  storage = "acme.json"
  entryPoint = "https"
  onHostRule = true
  [acme.httpChallenge]
    entryPoint = "http"

And by and large, this is working fine. I can see many frontends in Traefik, including this one:

However, if I look at the Traefik logs, to check on the status of LetsEncyrpt certificates, I'm getting this error:
time="2019-04-11T03:24:06Z" level=error msg="Unable to obtain ACME certificate for domains \"sync.\" detected thanks to rule \"Host:sync.\" : unable to generate a certificate for the domains [sync]: acme: error: 400 :: POST :: https://acme-v02.api.letsencrypt.org/acme/new-order :: urn:ietf:params:acme:error:malformed :: Error creating new order :: DNS name does not have enough labels, url: ",=

Spoke with a nice guy on #Traefik and he? suggested that traefik was trying to generate a cert for 'sync' instead of 'sync.pinguinshow.com' but I'm not sure why? it would be doing that. Any suggestions on a fix?

Solutions/Answers:

References