[All flavors] Missing (battle.net?)-whisper names in chat under certain conditions

[Luckyone961]

I've encountered the following issue across classic/cataclysm/retail:

The name of the player sending you a whisper is missing in the ingame chat if the following conditions are true

1. Your current character name matches your battle tag name
   1.1) (unconfirmed) The other players character name matches their battle tag name as well
2. You and the other player are in the same guild
3. You do not have the other player on your friendslist

You can still see the message ingame, but have to guess whos chatting or open up your battle.net app and click on the
unread messages in the top right. This will also give you the players battle tag name even if you are not friends.

Example of ingame chat

Example of battle.net app chat popup

Note that the above is not 100% reproduceable every single time, which means there is probably another variable condition which I'm not aware of.

[Meorawr]

Could the other variable condition perhaps be explained by the player cache on your client - or in other words, does it maybe work correctly if you physically see the player before you first exchange whispers?