I tried to comment on a question and point an user using @username but autocomplete is not working
May I know why it is happening?
I am using Google Chrome
Comment auto-complete will not work if the person you are referring is the owner of the post, because the owner of the post will be notified anyways, so its unnecessary there.
Note:-(As mentioned by Shadow Wizard)If there are multiple users commenting on the same post, then it will work, so as to properly refer whom the notification be sent.