Mentions (@[user name]) are currently disabled for all anonymous and partially anonymous discussions (c.f. https://community.canvaslms.com/t5/Student-Guide/How-do-I-mention-a-user-in-a-discussion-reply-as-a-...; note that there's no explicit discussion of the partially-anonymous case!). At least for partially-anonymous discussions, it would be helpful to be able to use mentions, so that users get notifications when they are being addressed (for example, when I'm responding to their questions in a Q&A discussion). I checked with a Canvas help-line rep today (case # 12760876), and apparently there's no way to enable mentions on partially or fully anonymous discussion threads. There's no warning about this limitation in the discussion thread anonymity settings menu, so I was unaware until after students started using one of these threads, and it's apparently not possible to change the anonymity settings after students have posted in a thread (which makes sense!). Now I'll have to awkwardly replace that in-progress discussion thread with a new one, if I want to be able to use mentions to reply to students. There's nothing stopping me from typing students' names in plain text, so there's not much use to disabling mentions; instead, there could be a warning in the mentions pop-up box reminding the user that the discussion is partially anonymous and asking them to make sure that they really want to be using a mention.
Either enable mentions on all partially-anonymous discussions, or even better, add another checkbox in the settings, maybe next to the "Anonymous Discussion" options, to determine whether mentions are enabled. For partially and fully anonymous discussions, that checkbox could default to "disabled" (mentions not allowed). Unlike the overall "anonymous discussion" setting, the "mentions allowed" setting should be modifiable even after posts have been added to the discussion.
