I put a new item in my wardrobe - the Flashback Wild One Cigarette - over an hour and a half ago. It has yet to turn up in it, I've done everything to make it turn up. It hasn't. When do I scream, throw a tantrum and file a ticket/make a bug thread?

have you tried physically searching it in your wardrobe? If it doesn't show up you can also do an account search to search where it is. If it says it's in your wardrobe then file a ticket because it's there just not showing up for some reason
Yeeeeeep. Cleared cache, restarted browser, searched my wardrobe, did an account search that says it's located in my wardrobe but when I open it, it's not showing.

that's really strange. I would file a ticket if it still doesn't show up
My items show up immediately when added, too. But once a item got lost in the void when I added it to the wardrobe and a programmer had to give it back to me, so I advise you to file a ticket.
It's resolved in the Problems & Bugs section. https://subeta.net/forums.php/read/874771/Missing-Wears