The item disappearing isn't a technical issue - ebay removed it for some reason.
Nobody here (other eBay users - eBay does not participate here) can see or determine anything about that link you provided other than the listing has been pulled and results in an error.
You should have gotten an email from eBay if the listing was removed explaining why.
No idea what the issue is with your Sold items page (or what page/view you are using)
Those links don't fail, and I can see the correct total for the last 60 days / 31 days. But the listing doesn't show up. I think I may open up a dispute to try to resolve this, or at least bring it up with eBay to get some clarity.
Ebay indeed is having issues with the search engine and/or items not showing up. There is another thread where others are also experiencing technical issues due to fail searchers. As your item being sold and not showing up , it might have something to do with the technical issue where customers can't pay for items and it might be in limbo. There is also another thread about customers complaining they can't checkout. I do advice to call ebay as it might be a checkout issue.
