As per title. The vast majority of user mentions do result in alerts, but some members aren't getting all of them. I've confirmed that they don't show in the alerts page. It seems to be occurring on large threads (often 10-100 pages in length with many participants) but I'm not certain it's restricted to them. Is this a known issue? I did previously have a user tagging add-on (bd) that would enable users to tag certain groups such as moderators however I've now removed this and the issue persists.