Update on 1/16/2020 at 19:00 PST
Here are some additional issues that we have identified and are actively investigating:

When items are returned in the mail from the Auction House, it can incorrectly contain more stacks than the displayed maximum of 16. This makes it look like some items are not being delivered. You will know if you are experiencing this if a mail appears empty but can’t be deleted.
- To retrieve the missing items in this scenario, take out all 16 of the displayed stacks, then close and reopen the mailbox to see the rest (you may need to repeat this several times).
If a character buys commodities in high quantities, they may not be able to access their mail.
The favorites list is not saving properly.
We have resolved some of the issues causing the “Internal Auction Error” to pop up, but it is still occurring and we are continuing to look into it.

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We’re aware of and working on a number of issues with the new Auction House:

The Upgrades Only filter can show some wands and shields that are not upgrades.
While selling certain items, non-related pets will sometimes appear in the list of current auctions.
Players are sometimes unable to buy out an auction in which they are the highest bidder.
Sold auction rows can disappear from the Auctions tab.
Sold auction rows can display the wrong quantity sold.
There is no chat notification when an auction sells.
The Uncollected filter can show owned battle pets.
While selling a caged pet, the price columns are misaligned in the list of current auctions.

Some players have experienced attempting to cancel an auction that has bids enabled, but no bids yet, and receiving an incorrect warning that they will be charged an extra 5% penalty. This penalty message is only meant to be shown if there’s an active bid on your auction. If there is not an active bid, you can safely proceed with canceling, and the penalty won’t be applied.

We’ll continue to investigate all of the above and develop fixes wherever possible. If you’re experiencing any issue with the new Auction House, we suggest you first disable your addons and try again.

Thank you!

Auction House Issues