While I personally don’t know, according to the Blue post from a French-language forum (translated & quoted above) they have supposedly fixed the issue and the matter is now of restoration, which will be time consuming.
I HOPE they are right in this and that we will eventually get the stuff back. I don’t know. I am very much keeping my fingers crossed.
How is it possible this is one of the most commented threads here I have ever seen and I can’t find a single response on it from blizz anywhere? Huh?
ahhh the ol good trademarked Soon response. In case anyone is wondering Blizzard GM’s have been responding soon to my tickets for over 4 weeks when i first reported the issue via tickets as well as bug reporting, so yeah Soon. Can’t wait.
And we’re missing out on one of the best times to make a profit on those old mats, at least as far as I’ve noticed. New xpacs seem to make everyone want to level up professions, so they’ll just spend insane amounts of gold on the mats they need. With all those old mats missing from our banks, we have nothing to sell.
I haven’t posted on the forums for a while, but I’ve been keeping an eye on them. Items from both of my guilds’ banks (Alliance and Horde) are still missing; overall, the Horde bank is wiped out, but the Alliance one only lost a few.
The only recent instances of items going missing are those near the new item that was added. However, this was a few days ago, and I haven’t checked on it today. Either way, I’m not going to mess with the guild bank anymore until it is fixed.
I had years of experience playing alpha and beta testing with some of Blizzard’s games and other game companies. I found it really odd. They did not test out the interactions with the guild bank alongside the warband bank as a whole.
Many other game companies would put time into any new system and make sure it does not interfere with any other inventory system when they add something new to it.
This is the outcome of selling beta testing. This is what you get. 
Try to be more productive and less of a jerk about it. All I was posting about was the issue and the fact that Blizzard didn’t fully put in the time to work on it as they should have. Having sold a beta is not new to any company these days. The fact is, the game was rushed out and needed more time spent on it overall.
Not trying to be a jerk. I’m pointing out that when you literally “sell beta testing”, you’re not really achieving the goal of what testing is supposed to do, and it shows with the quality of the content being put out.
Well, sorry that I had misread that. Yes, the testing of the beta was not the best. They focused more on dungeons and raids than anything else, besides a few gear sets and trinkets. There wasn’t much else to it.
Has any Guild masters stuff from the guild banks been restored as of yet?
Just so I’m counted also. I’ve had somewhere around 500 items disappear from my guild bank. Just my wife and I are members. Probably a couple thousand Darkmoon Daggermaw alone.
Realm: Dalaran
Guild: Templars of the Sun
It seems to be that there are a lot of small guilds in this thread, Private Guilds or 2 person. Could it be that only the small guilds are affected? Or maybe there are a lot more small guilds than I realize? Or maybe larger guilds think that the items were withdrawn so didn’t check the logs?
I’m almost certain that a large percentage of ALL guilds were affected, its just that only small/personal guilds would have noticed. Without the logs working, I imagine large guilds wouldn’t jump to the conclusion that its a bug and look at the forums, they’d just assume people from the guild took stuff out/cleaned up for the new expac.
Chiming in to report my Gbank is gone and my guild isn’t small, but we’re not large either. But everything from all tabs is gone. Gold is still available.
Looks like some info is requested:
Realm - Gilneas
Guild - Inevitable
I have 11 guild banks wirh 7 tabs each. I have been building since classic 20 years. They were categorized all full and organized. Estimated: Tailor 60% wiped. Leatherworker 90% wiped. JC 100% wiped. Engineer 80% wiped. Food 40% wiped. Alchemy 30% wiped. Elements 100% wiped. BS 80% wiped. Enchant 100% wiped. Misc bags/quests/transm 40%. My level armor bank 10 levels ea tab was so spotty I cannot give estimate.
Hope this helps.
Okay I’ve had a reply by a blue on my post in the EU forums:
This is the main, useful part:
I have to say … I’m really grateful to Felranys for sticking with us through this and keeping us informed - even if it has just been “sorry, we don’t know yet”. The fact that there has been virtually no interaction from blues here on the US forums is just so sad and feels a bit disrespectful.
Across my characters, I have enough old mats to sell to make some gold. What is up with runecloth? Is there something going on with it that I don’t know about? Why is it suddenly (in the last few weeks anyway) 11-12 gold each? I’ve never seen an old mat go up that much unless there was a current need for it.
As for guild banks, I’ve finally caved. I need the storage space so I’m filling one of mine back up. It’s the bank of one of my auction characters and I’d use the bank to store stuff that rarely sold or buying stuff that was cheap and holding for reselling. I lost about half of what was in there, but now I just need the space. I’m filling it back up with stuff from all my characters via the warbank. It’s going to take a while, but I really need the space!
I had previously filled all the empty spaces with linen cloth and left it like that for a week or more and all the linen cloth stayed put, so I feel safe using the bank.
Just in case there is ever any restitution of lost guild bank items, here is a detailed list of my 14 personal guilds with their realms & my guild master characters. All 14 were affected with loss & disappearance of items. “Winds of Twilight”(Terokkar) gm Faradawn 7 tab bank is COMPLETELY emptied. The rest have lost between 30% & 100% of their contents. The 3 guilds on Farstriders realm have only a couple of tabs,but every guild on Terokkar & Alexstrasza have 7 tabs. The cost to replace all the missing items is well in millions of gold. I had to re farm & buy everything to level engineering at a cost of nearly 100,000 gold when I had all but a very few of the reagents, items, & mats ( all disappeared) in my devastated engineering/mining banks 
This includes
the “junk” from DF mob drops I needed to replace to get toys, mogs, mounts, & pets from the rep vendors)
ALSO, I realize they are saying they fixed the bug where stuff disappears out of our guild banks, but yet there are reports of things STILL going missing as of last week. Talking to some with large active guilds, yes they are missing things too,but with these disappearances leaving no log & many people in the larger guilds they have NO WAY to describe their item losses. My guild banks listed below are owned by myself & only have my own characters in them. No permissions to anyone else.
ALEXSTRASZA REALM
TEROKKAR REALM
FARSTRIDERS REALM (The 3 guilds below were for items/bags etc for new characters, rare BOE drops, pets, mounts, etc)
Also, could OP update the list of numbers affected in the first post if they have the time & kindness to do that? Thank you so much OP and everyone (orange text person too) for links, updates, and encouragement & for not letting this just fade away to obscurity with no resolution. I cannot believe our huge thread has no formal blue responses of its own. Disgraceful!
Adding my name to the list of people missing guild bank items with no withdrawal info in the logs. It happened in two stages. One day a lot of stuff was missing. The next day all but one item was missing. This is my personal guild. The only characters in it are on my account.
Realm - Cenarion Circle
Guild - No Consequence (H)
No… sadly.
Ok, so if the banks can be used again, that probably means they are going to mail our stuff to us. If they are holding out to restore everyone in one lump sum, I would rather they do it in increments, say all the accounts starting with the letters A-C. Then we would know that eventually they will get around to our account and that, indeed, the items are being restored. I would have much more patients if they were to do this.