BBPress @ not working

I have a BBPress forum with WordPress installed and Avada Theme. I am not able to use the @mention function anywhere on my forums within BBPress. I do not have buddypress installed. Strictly BBPress as my forums. Installed Plugins for the Forum are:
Ultimate Member and a few of there extensions
BBP Style Pack
Comment Mention
BBPress
BBP Notify
GD BBPress Attachments

Thanks for any info and help.

@with-username does tag them but it doesn’t give me a drop down of what users are on the forums and i cant figure out how to get it to do that.