Really Blizzard?
About 2 days ago in a Waycrest +13 Key, my whole group got disconnected mid-dungeon. We could instantly log back in, but the Key was over and now a +12. No Loot.
Today, Atal +13. We were fighting the last boss, as our group got disconnected again. Same as Waycrest, we could instantly log back in, the Key now a +12 and no Loot again.
This starts to feel like a waste of time, and all you hear is: “We can’t set your key back up to 13, you have to play it up again”. Yes that’s okay, but what about the wasted time since we didn’t get any loot?
I already heard this issue from other players aswell, so I am starting to wonder why there is nothing to read in the forum? You can’t tell me that noone has complained yet, so where are these posts going and what is Blizzard going to do about these group-disconnects?
There are a few things coming together here that unfortunately end up being a rather unpleasant mix. Fair warning in advance: lots of text ahead.
An entire group disconnecting from a dungeon at the same time is usually the result of a shared factor between several members of the group, such as similar connection routes (which have some form of flaw to them) or even addons (we’ve seen a few that can actually disconnect players). Server-side issues are of course also possible and have most certainly occurred a couple times in the past, but typically those would have larger impact if and when they do happen - if a server actually goes down that typically takes every player on that realm offline, not just a select group of individuals (exceptions do exist, but rarely).
We’re constantly monitoring for such issues and indeed at nearly any given time have at least a few larger-scale networking issues across european internet service providers on our radar - and we actively try to get those sorted out in the background via cooperating with the affected ISPs so ideally players never know there was a problem in the first place. Obviously that is not always working out, and when it does not the result may be just as described here.
That honestly is a pain, and we very much share everyones frustration in such cases - if the game does not work as it should, even if the reason is utterly outside our control, that is just not a good time for anyone.
The other part here is what we believe to be an actual bug in the game itself, namely that there are conditions that can lead to no loot being generated if a dungeon is first interrupted via the group leaving it (e.g. through disconnection) and then running the same dungeon with the newly downgraded key. It has proven excessively tricky to reproduce the exact chain of events that could potentially lead to that result, but we know that this does happen at least occasionally and we want to sort that out as soon as we can.
As per usual there’ll be updates on that once we have them, most likely in the form of patchnotes - and we would very kindly ask everyone who encounters these circumstances to use the bug reporting tool within WoW to submit a report right then and there. Half of the work in fixing a bug is to fully understand how exactly it occurs, and the data collected in bug reports can go a very long way towards that goal. Thanks in advance! 
But, why would that result in the dungeon being reset? That’s the server messing up, no? Or do you have some stupid system that resets the dungeon if everyone in a group disconnects?
It’s also very unlikely that any shared addons when people are using pre-built, none or custom-built UIs would cause the whole group to disconnect exactly at the same time AND ALSO RESET THE DUNGEON after the DC.
You can’t just reset a mythic plus dungeon while you’re in it, even when people are inside disconnected it will tell you that there is someone inside if you try to reset it, unless they’ve been disconnected long enough for their character to disappear. That has to be the server messing up when it gets reset after a group-wide disconnect like that.
So I see this problem still exists. I´ve heard from guildmembers that they are getting a DC during the m+ and key is depleted upon login. Same thing happened to me today in Mechagon +. It´s been more than a month now, can you fix this issue please? We wasted 30min of our time to just stand in front of the final boss and getting dced.
Same thing just happened to us, must have been the same time it happened to you guys.
Yeah could be. Not sure about the exact time it happened.
But this is not acceptable. In our case it was just a +2 and we are good geared for it but we just wanted to check out mechagon +. Now imagine the same thing happening in a high key run at the end.