User's name not being picked up by @@ superping suggestion in chat

Question

I have a user, whose name is 2012User. When I try to superping them (@@) in the public 3DPrinting chatroom, with @@2012, their name does not appear in the auto-complete user search suggestions box thing¹:

They have a rep over over 100 (192), they have posted questions on the 3D Printing site, so they are an established user. Why is superping not working, or rather, why is their username not listed in the user suggestions?

Note that @@[email protected] seems to make the user suggestion work correctly, but it is rather longwinded:

I do wonder if it is the old issue of 3DPrinting's site name causing issues again? See 3DPrinting question URLs aren't parsed in chat [duplicate]

I have tried pinging them with both @@2012User and @@[email protected] but the latter doesn't appear to resolve the name correctly, and ends up looking like this

@@[email protected] please join us in chat 

whereas I'd expect it to look like:

@2012User please join us in chat 

Also, I'm not sure if either of them (@@2012User or @@[email protected]) worked as the user has not responded.

Note that other users with usernames beginning with numbers appear in the user suggestion just fine, as the first screen shot shows, just this particular user.

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¹ I don't know the correct term for this UI component

Answer 1

Because the user doesn't have a chat account yet.

I just tried searching their username in the list of all chat users and got nothing:

Only users who already have chat accounts can be superpinged just by using @@<username>. For a user who has a site account but not yet an account on Chat.SE, you need to superping them using the <userID>@<site> syntax.