https://community.letsencrypt.org/t/2018-01-11-update-regarding-acme-tls-sni-and-shared-hosting-infrastructure/50188
This issue has disabled the verification method for new users. People grandfathered in are OK.
golang/go#23426
The go team is looking into it, but the LE team is saying to move towards HTTP-01 or DNS-01 methods.