So there's no evidence you prepared the 2018 return? If not, then you probably have multiple accounts without realizing it.
The email address you see on your notifications is not necessarily the correct User ID.
You can have up to 5 accounts that use the same email address for notification purposes. A User ID may be an email address, but it doesn't have to be. It might be only part of an email address, or it can be anything at all.
See my answer below on how to troubleshoot.
