SC2Mapster

Okay, I've found out the source of it.
It's because you've used special BattleUI frame as custom layout frame for loading screen.. BattleUI is actually root frame for Battle.net UI. Apparently trying to use it for loading screen is pretty disruptive :D And something from SC2 cannot recover without a full game restart.

By curiosity I've tried to use couple of other frames that should not be used for loading screen, but none of it resulted in broken game.
I don't know what made you use custom layout, and why did you actually pick BattleUI. But this together was worst case possible, haha.

Generally editor should report about issues like that, but I haven't been seeing anything in the log. So it took a while to find.
In fact it can be considered as bug, because ideally maps should be sandboxed in SC2. That is nothing you do inside the map should affect the game itself after you quit the map. And destroying Battle.net UI is certainly something that negatively affects user experience ;D

To summarize, to fix it just just go to *Map -> Map Loading Screen*. Unlink *BattleUI* frame. OK.

Okay, I've played with this for a while, and I must say the Allied Commanders mod is not the one to blame. I've dettached it from your map, and also removed quite a lot of other things.. and this weird behavior is still happening.

This is what I'm observing in my offline tests:
If I launch your map while being logged in SC2, then I quit it and I'm back at login screen. That means I've been silently disconnected. Also I have black background on login screen, instead of planets. But what's most important I'm unable to login again unless I restart SC2 (it hangs on 'Authorizating..').
If I launch your map while having SC2 closed, then after map is loaded I quit it (just the map). And that also results in ability to login to bnet.

This is veeeery weird. I'll get back to this later.

What I can tell you know is that I'm getting the same issue when I'm trying to watch replay/resume it. In fact you're already disconnected before the map reaches post init phase - that is before loading screen is gone.

And the source of it is certainly Allied Commanders mod. I'm not sure why though. Likely it might take use of some blizzard exclusive functions. What results in disconnect when done online (probably because publisher's account doesn't have necessary permissions).

Although I've read about people using this mod before, w/o any disconnect. So it might be new thing - coming either from recent patch, or update to the mod itself.

Also it's worth to check if your local version of this mod is the same you linked against in Battle.net (that is v0.36).

So the question is, do you actually need this mod - are using anything implemented there?

I'll try to identify what exactly this mod does during its initialization process that ends with disconnect from bnet. But if you want easy fix, just remove this mod from your map dependencies.

One thing that I noticed before trying out your checklist.
When I launch my published map through SC2, while the editor is still running in the background, the Editor spits out these error messages when the map causes the disconnection:
"[10/6/2017 11:52:38 PM] Warning: Battle.net connection is closing: You have been disconnected from Battle.net because another computer connected using your account.
[10/6/2017 11:52:38 PM] Warning: Battle.net connection was lost"

That is normal. Editor acts as SC2 client. So when you login in it to the same account and region, and then launch SC2 for the same account and region, you get this exact message. Since server only allows one active connection.

Nope. There's nothing special you need to do, for your map to work correctly in Battle.net. The behavior you experience is either caused by some obscure bug in SC2 which reason I cannot guess. Or there's *something* in your map that causes this freeze.

It's good that you were able to save the replay. And what's better, it seems like the bug can be reproduced by running the replay.
If you could attach the replay here, or upload it somewhere and post the link, then I'd look into it myself (yes, replay from online game is all I need). If the bug will also occur on my end, I should be able to track down the cause.
Also, what's the length of the replay? Because if the freeze actually happens right after start, I'd expect it to have ~0s.

In the meantime, here's small checklist you could do, to narrow the area. Proceed it until you'll confirm the freeze doesn't happen anymore.
(Of course before doing anything of this, backup your map.)
- Simply republish the map w/o changing anything. To make sure this is not result of some error during publishing process.

- Remove custom dependencies/mods (if you have any). Publish & retry.
- Remove triggers that are running at the start of the game. Publish & retry.
- Remove ALL of the triggers. Publish & retry.
- Remove ALL preplaced units on the map. Publish & retry.
If at this point the freeze will still be occuring, I'll be suprised. But you should keep going and remove remaining things such as: custom imported assets (if you have any), lobby attributes/variants, data entries.. it might sound funny, but I'm serious - when you can't guess the source of your trouble, then removing the possibilities piece by piece is smart way to approach it.
Unless you'll end up with empty map, haha.

Given the fact it works flawless in test mode, it does seem pretty weird.

I could see infinite loop in triggers or infinite recursion in Data causing something like this, where game freezes for a while thus putting you in a state of being not available to Battle.net. Although in such scenario it should unlock after a while - when SC2 detects things went wrong, to put it simple.

But.. if you can't reproduce it offline in test mode, I don't think that's the problem you're running into.

Does the disconnect happen every time? Are you able to quit the game before getting "attempting to reconnect" screen pop up, and have a score screen visible? Does the replay file save after the game?