Yeah that’s one of their standard bot replies. They’ve already said that making tickets will have no impact. They’re aware of the issue, they’re working on it. Any items that got vanished will be sent back automatically - just no timeframe yet.
Making tickets at this point is just clogging their system … hence the bot response. I’ve seen a message before stating that the bots are used when their ticketing system is getting overwhelmed.
Latest GM response:
There is currently a bug so that items from the guild banks are not visible and the bank shows empty even though nothing was taken out.
The developers are informed about this issue and we hope that it can be resolved very soon.
Sadly there is no eta yet and no workaround or fix. However:
The developer are very certain they have fixed the issue itself so it will not happen again going forward and that they were able to identify all guilds that had the issue.
They are currently working on a solution to restore the lost items to the affected guilds. We don’t know yet how this solution will look like (for example it could be mailed to the guild leader or directly put back into the guild bank).
I would recommend that you put no further items into the bank until the issue is resolved (if you already did maybe take them out for the moment).
IMPORTANT:
We can’t promise that everything can be restored but when something like this happened in the past the developers were able to recover everything, so we hope that will be the case here as well and that’s that the developers are aiming for. The goal is that nothing will be lost.
I am sorry that we can’t do or say more atm. but we are waiting to hear more on it once it’s resolved.
Best keep an eye on https://worldofwarcraft.blizzard.com/en-us/search/blog?a=Blizzard Entertainment as well, the devs post the latest bug and hotfixes there every other day. So once the issue is resolved I would imagine they will mention it there as well.
Hello all 
Quick update to confirm that work on this issue is still ongoing with high priority, devs are doing everything they can to pursue the best resolution possible, as quickly as possible.
We’ll try our best to keep y’all update with the latest info as we get them, thank you once more for your patience! 
Thanks for keeping us up to date Felranys its not what I’m used of from Blizzard these days. So thank you for the effort.
As to it not being fixed yet: 
Thank you the update Felranys 
It’s a busy time for the Devs, fortunately The early release has been very, very smooth. I have only encountered one significant bug 
. ( I did report it )
Meanwhile, I could use some extra gold to buy all the tabs in the Warband bank 
Hey … thanks for that!
Someone posted on the US forums that they’d had a GM say this:
If true, it suggests they’re planning on restoring missing items automatically soon. Is this true?
Can you also please let us know if our banks, as of now, are “fixed” … meaning: (a) nothing else will go missing from them (so we can start using them again) and (b) nothing we do with the vaults now (ie, adding or removing items, moving stuff around, etc) will affect the outcome relating to our returned items?
Because other than the initial issue of missing items, we now have a lot of people scared to use their guild vaults at all - either because they’re worried more stuff will go missing, or because it will “over-write” something that may be already there that can’t be seen, therefore affecting their chances of getting everything returned.
Thank you for all your efforts (and the other guys) on this … and yeyy for the EU leading the CS way on this matter 
There’s HUGE threads on the US forums, with virtually no (or no) blue responses … which is a nice change for us in the EU 
My ticket has been closed but still no items in guild bank.
They’re closing and marking “resolved” tickets relating to this … because those people can’t resolve that issue. They don’t need to attach the issue to your account as, in theory, they’ll be doing something behind the scenes to automatically send lost items back to people. So as far as they’re concerned, the issue is closed.
Admittedly, giving out more information, quicker, would be a much better option.
Happened the same to me on the patch day, all tab 1 and half of 2 of my guild bank vanished, i’ve send some reports, tickets… Nothing clear, dont know when they fix it or if they are going to return us the items, the worst thing it happened again to me today on Warband bank, i was thinking its safe for the rest of my bank and items, but seems not, are we going to lose everything?
My items are gone too. Pretty concerning and a real shame.
Thought they had done something to prevent this from happening again but as of today my guildbank is almost empty. My 3 tabs with pets from different events is totally empty. I spent hours and hours on alts to collect these pets. I can’t get a new one from my guildbankanymore when I sold the one that is in auction now. This bug is costing me a lot of gold.
I collected all radiant echo gear and all weapons during the pre-patch event. I put them into the warbank for later use. Many had tertiary stat and gem slot, too. I have thought, just for fun, I will create some level 70s for random BGs.
Now, all items have disappeared. At least, the bags are still there…
Stupid me, what a waste of time was that! 
The same situation here. All Dalaran Defender equipment and wepons are gone from the warband bank.
They’ll probably be able to restore it sometime between now and the end of Worldsoul Saga, but this is just sad.
I’m just glad I didn’t buy TWW.
I read in the blue posts that at least they now stopped it from happening further? Well that is not correct. This morning I wanted to put on my pre patch items on alts and I lost all the items, in the warbank. My warbank was fine a few days ago so what is going on here and where will this stop? Are we going to lose items from our bags too in the next days? or our personal banks? This is now really getting a bit too much tbh. And on top of it al we are losing items now on the AH as well. Come on now get your act together, this isnt a 10 dollar company.
Same here. Spent all my pre-expansion currency on gear yesterday and put it in the warband bank. Today, all of it gone. Not the gear from other expansions, or the mats etc. Just the pre-expac gear. 210,00 residual memories worth. So now I can’t trust my guild bank or my warband bank.
Same problem. Unequipped items in warband bank are gone.
But probably this is not related issue. Some “clean up unused stuff” script at the end of prepatch event, have no idea why. And unequipped items in personal bags are still here.
This is actually a different bug, completely unrelated to what happened to items in some Guild Banks.
On the bright side, those items are not actually gone but simply not visible. That said, a fix is being worked on to make sure they appear again
Guild banks are “fixed”.
To the best of our knowledge, the problem that caused items from guild banks to disappear was found and sorted a few days ago; it should be safe now to use guild banks again.
‘Safe’ maybe, but I am still missing thousands of gold’s worth of goods. Some of them literally irreplaceable as they’re not available in game any longer or will need to be regrinded over months. In the meantime, I am leery of using either bank. Honestly I feel like I’ve been burgled, which may sound like hyperbole, but when your guild has been going since TBC and some of its contents stretch back that far, logging in and finding half your goods missing really hits you where you live.
Glad to hear the warband bank issue is less serious but you’ll understand I’m sure if I wait and see the fix come in before I use either again.
Safe to use, but the part of restoring our items is still being worked on correct?