Yep. There is even a help page saying to click the particular mailing list you're attempting to add to, then click on add subscriber and select "manually add email". But THERE IS NO SUCH BUTTON! The only option is to "add subscriberS" it's that plural s that messes it all up. From there in only allows "importing a cvs file with 3 columns"
Gah.
I just want to type an email into this list that I pay a
lot of money to create and have access to all in one place. Better just go back to mailchimp.