Odd behaviour when moving torrents

[RetroViking]

So this is the scenario (Windows 10):

- Had a few downloads lying around the desktop. Big files, around 30gb each
- Right clicked said files in qbittorrent, chose "set path", moved them to a different folder so they don't stay on the desktop
- Everything moves instantly, except for two file folders.
- Wait for about 20 minutes, they're still there on the desktop; meanwhile, bittorrent is using 100% disk
- Close qbittorrent, still runs at 100% disk for 20 minutes more
- Bittorrent process closes, one of the two remaining folders dissapears to the new location; one folder is still left on desktop.
- Restart qbittorrent, all of the moved torrents say: files missing
- Press the start button on one of them to see if that forces recheck, starts redownloading instead
- Close qbittorrent, move the files back to the desktop
- Open qbittorrent, 'missing files' is gone, except for the one I accidentally restarted downloading earlier. It succesfully rechecked.
- One of them still has missing files. Turns out, this one is the only one that had its path updated, so I had to right click and set its location to desktop because, as I said earlier, I moved all of the files back to the desktop so they would seed.

There is only one drive and partition on my computer.

So... did I do something wrong? If it succesfully moved some files, why did I have to move them back to the desktop for them to seed? How can I prevent this in the future?

And most importantly, can I trust the integrity of those files? It would be annoying to redownload 100+ gigs just to make sure I didn't screw the files up by simply moving them to another folder.

Thanks.