Tagging in body of 'update' vs. just tagging to notify and email notifications

My team has said just @notifying someone on an update is not sending an Outlook email notification, and they have to tag in the body of the 'update' copy (e.g. Hi, please approve this copy @2671087) then they also notify them in the proper area. I'm trying to find which setting this is tied to. Preferably they would just @notify them and not also have to add their name to the message.