When writing text in fields, you can type “@” and the beginning of a person’s name. An autocomplete list of matching people appears, and you can select a name.
Help refers to this feature as a “Special GitLab references” in the superset of Markdown. Help calls it a “specific user” reference.
Recently, this feature has stopped working when typing the names of people in group X. That is, their names do not show up in the autocomplete list after typing “@”.
We have not adjusted the rights or permissions of group X. Also, the people in group X have not reported a change in their access levels. This is just an impact to their names showing up when “@”-ing them in text fields.
Our internal GitLab instance was recently updated to 12.6.4-ee. I do not know the previous version.
I am assuming this is a bug in our current version of GitLab. Then again, it might be some security change. I can find no report of the bug in GitLab issues.
We could start fiddling with the rights and permissions of group X, but I am wondering if someone else knows precisely what this problem is and how to solve it.