She may not have known there were problems until after she ordered. My post office lost me three packages in early July and I had no idea it was going to lose them until packages that had been mailed later than those started arriving and those three were nowhere in sight. It's like their reliability went on vacation or something. (I do wonder if their reliability can be traced to a single person who went on vacation, honestly, and if so I would like to know who it is so I can avoid getting things sent to me when they're not in.) These were trades so I didn't request that packages be resent (though two were), but if they'd been sales, I probably would have, and I would have expected the seller - especially someone with 800+ sales who I assume can afford to replace a lost item - to do it. If you don't have that specific bracelet, you could ask her to pick something else from what you do have in stock?
I mean, yeah, go through the appropriate channels if you can to make sure the package hasn't been delivered, but I like to assume the best of people and I don't think it's a wrong trait to have. It's not her fault the package was lost, even if she'd been having trouble with her mail service before she ordered. It's her mail service's responsibility to make sure things get to her, and I hate the idea of having to, what, not shop online because some people aren't doing their job right? Gosh.