What, exactly, is wrong with in-game chat?

I've seen a lot of complaints about the game recently, and you know what keeps on popping up most often? 'Chat is broken'. This comes up more often than anything else - more than connection issues, balance debates, or anything else related to the game. Sure, I haven't played as much as the average member here, but I can say for sure that this is one of the most despised and frustrating flaws of Resurrected.

The chat system is apparently so broken that people resort to using Discord, the Bnet launcher (lol), and pretty much anything else that they can use by alt-tabbing out, instead of using the in-game chat system. I've heard that it wrecks multiplayer on all levels, makes the online experience feel like a glorified single-player game, and won't let you leave the /trade channel. It really does seem like a deep and entrenched issue that is really hurting the game.

But what I haven't actually seen yet is a good, detailed summary of every chat issue written in a way that the devs can easily understand and do something about. Why don't we make an effort to list each issue here one by one, with detailed step-by-step instructions to reproduce the issue on the live client, a detailed background/description of the issue, suggested solutions (explained clearly), and any other pertinent details?

This way we could present this topic to the CMs on Reddit or something and maybe get the point across that in-game chat is utterly broken, giving them some actual digestible information to work with in producing a fix. My suggested format is the following, but feel free to add or remove any you think aren't pertinent to your specific chat issue. We could also use this opportunity to ask them questions (what is the actual tech/stack powering the current system - is it actually IRC or is it some newfangled thing?).
Name of issue:

Device, game mode, other tech info:

Description/background of issue:

Step-by-step instructions to reproduce the issue:

Expected results vs Actual results:

Suggested solution(s) or improvement suggestions:
If you want to copy paste the template/formatting for your post, here's the full BBcode:

Let's try our best here and try to bring some clarity to the 'chat is broken' issues so that we have a good reference.

As so often...Teebling for the win! Can't you just join the Blizz team and fix it for them or something?

Name of issue:
Player chat not visible

Device, game mode, other tech info:
PC (possibly consoles, no idea), any multiplayer game

Description/background of issue:
Each game has a dedicated game chat lobby that each player should automatically join when entering the game. The members of this in-game lobby can be listed with a simple /who command in game chat. In order to chat with one another via in-game chat, both, the sender and the audience of the chat message must be in the game chat lobby. As is, the auto-join of this chat lobby does not work more often than it does, resulting in only some or none of the players in a game actually entering the lobby. Joining the lobby is independent of being the game host or joining someone else's game. Either scenario has a high chance of failure for your joining the game chat.

Step-by-step instructions to reproduce the issue:
1) Create or join a multiplayer game
2) Have other players join the same game (if not already present)
3) Execute a /who in game channel

Expected results vs Actual results:
Expected:
The /who should output each player in the game.
Communication between all players in the game should work fine via in-game chat.

Actual:
Option A: /who doesn't output a single name (because you yourself failed to join the game channel)
Option B: /who only outputs a subset of the players in the game, including yourself (you successfully joined the game channel but the players not listed did not)
In both cases: Only players who successfully joined the game channel can actually see each other's chat messages.

Suggested solution(s) or improvement suggestions:
Ensure players correctly join the game chat channel/lobby upon joining a game.

Name of issue:
Unwanted chat flooding screen

Device, game mode, other tech info:
PC (possibly consoles, no idea), any multiplayer game

Description/background of issue:
The in-game chat is theoretically designed to work in channels that you can choose to show or not to show (e.g. "game" vs. "all"). This restriction however does not reliably work unless the message window is currently open (that is you hit M or Enter to bring up the chat entry window). If the window is not open and chat is merely displayed as it comes in, you reliably see ALL chat, regardless of what your channel is set to.

Step-by-step instructions to reproduce the issue:
1) Create or join any multiplayer game
2) Set chat to "Game" (or leave as is since Game is the default)
3) Make sure chat window is not currently active
4) Wait for someone to do their usual trade chat spamming

Expected results vs Actual results:
Expected:
Only game chat should be visible as it comes in.

Actual:
Trade chat is shown as people submit their messages there and completely floods your screen (since those same people are in a habit of linking 50 items back to back).

Suggested solution(s) or improvement suggestions:
- Ensure only selected channel(s) are visible, regardless of chat window activity status
- Allow for functional leaving of a channel (to be remembered across games) so we can /leave trade chat and then use 'all' for game chat and private chats, without being trade-spammed

Name of issue:
Private messages not visible

Device, game mode, other tech info:
PC (possibly consoles, no idea), any multiplayer game or lobby

Description/background of issue:
When sending a private message (/w) to a new player (or receiving one from a player for the first time in the current session), a new private channel is created. Both players automatically join this channel and have it set as their current active channel. This channel should show all messages between both players.

Step-by-step instructions to reproduce the issue:
1) Log in with account A
2) Log in with account B
3) Join lobby or an online game with both accounts
4) Use /w to whisper account A from account B

Expected results vs Actual results:
Expected:
Private channel should be established.
Both players should auto-join the channel and have it set as active.
Message should be visible to both players.

Actual:
Channel is established, joined and set as active correctly. However, the first message sent is always lost and will never be visible to the receiving player. Only a 2nd message and onwards will be shown.

Suggested solution(s) or improvement suggestions:
Ensure all private messages are shown to their recipients.