Why can the certificate not be found by the Ingress Controller, while the certificate has been issued?
https://github.com/jetstack/cert-manager/issues/482#issuecomment-449664935


  Once I followed this
  https://github.com/jetstack/cert-manager/blob/master/docs/tutorials/quick-start/index.rst#step-6---configure-lets-encrypt-issuer
  and deployed the issuers in the namespace of the app, it works