Black arrow up and down

[Snillegutt]

When torrents are finished and moved to folder for finished downloads, arrow points up(usually black)

But, sometimes, even if the download is completed 100%, arrow is black and points down and files are not moved to finished folder, but stays in temporary folder.

Why? Is it finished for real?

[paolovador]

I have an occurrence of a torrent in this state: the download is marked 100%, stalled, but 1 file inside is only at 89.7%.
Of course the torrent is not finished so it's still in temp folder and marked as stalled, but why the pourcentage is at 100% ?

Thanks for any input