I am feeling pretty dumb this afternoon. I was trying to put some pdfs onto my iPad via the kindle app (that way I can keep all my graphic novels, comics etc in one app rather than having them spread around) so on my laptop I dumped them into the 'send to kindle' page and off they whooshed. However they weren’t showing up in the iPad kindle app despite them showing up in the library of my actual kindle. I was troubleshooting for about fifteen minutes and then I realised that although the library in the iPad app was sorted by most recent, it was being sorted by recently READ not recently ACQUIRED, so I just scrolled all the way down to the bottom of the list and found them 3 copies of each file sitting there from when I’d sent them multiple times thinking they just hadn’t worked.