Tagging a second name in a post shows as a hyperlink but doesn't notify the person

If one reply's to a post, the original poster is automatically tagged and notified.  

However, if one adds an @ sign and tries to tag additional people those people are not notified.  This lowers your website traffic because you're not notifying these people directly.  Additionally, in the past, this used to work.

Expected behavior

- Typing '@' in a post should bring up an auto-complete form with poster names

- It should notify the @ mention in the same way it notifies the person you're directly replying to