Can't tag editor on comments

Hello! Can someone help me with the following.
I need the content manager (she has editor access) to be able to change some text on the site, but I want to add comments to her so she can see what I need her to change, but when I @hername she doesn’t show up I can only tag people with admin access.

But on the documentation it says I can so I am confused I have re-invited her as an editor but I don’t think that will fix it.

Here is my site Read-Only: LINK
(how to share your site Read-Only link)