Account search isn't showing the correct information for me. I've checked with several different items and for all of them it claims that I don't own the items even though I know that I do.
As an example I have a Ruby Crowned Kinglet in my vault

But when I do an Account search for it all I get is the shop search link

Not sure how long this has been happening but I noticed it yesterday.
[Edit] In order to keep all the information in the same post I'll add these bits here as well.
What browser are you using?
It should actually say right under the "Search Shop" if the item was found or not - but I don't see the text in your screenshot.
This is what it shows for me (I don't have it):
I'm using Chrome (latest release update). And yeah, it used to show the information correctly. Oh, and I noticed (after making the thread) that my bookmarks on the side don't show up on the Account Search page, and that if I mouse over the item it doesn't even try to load the pop-up information thing. It's acting almost as if that wasn't a thing at all...
And I've cleared my cache and done hard refreshes but it still doesn't work for me :/
Any custom css? I bet thats it since your missing that whole tag
It's not my custom css. I removed all of it and checked the Account Search again and it was still doing the same thing. Also, I haven't touched my custom css for months and this weird thing started happening a few days ago. Before it was working perfectly fine.
Any chance you can view-source and share? Or at least look and see what it's doing after search detail.

Item ID: 180329
Shop Search
<style type="text/css">
.remove-link,.mass-remove-link{font-size:90%;color:;font-weight:bold;}
.remove-link:hover,.mass-remove-link:hover{cursor:pointer;text-decoration:underline;}
</style>
<div>1 item(s) found in total!<hr /><p>1 found in your <a href='/explore/vaults.php?vault=item&act=search&category=-1&sort=name&order=asc&name=Ruby+Crowned+Kinglet'>Vault</a> | <span class='remove-link' role='link' data-itemid='180329' data-loc='vault'>(Remove One)</span></p></div> </div>
Does account search work in incognito mode?
There was Account Search isn&;t Working and I think it turned out to be a broken(?) extension in Chrome? Their page looked like yours, cut off after "Shop Search".
It looks the same for me in incognito mode. But I guess it's worth a shot to test if any of my extensions are at fault. Will have to check that later though as I am about to go afk for a few hours now. But thank you for the information. Hopefully I'll be able to solve this mystery soon ^_^
[Edit] I just went through the extensions I have on my Chrome and disabled them one by one and checked the Account Search page after each one that I disabled and nothing changed. I also disabled all of them at once but that didn't make any difference either. So, I am still at a loss.
I also just tested it using Opera instead of Chrome and the same issue happens using that browser as well.