I had a problem with an incomplete download. I have a partial
file on disk, and when it gets put into the download section of
the GUI, the progress column shows 0% - it should be around
39%.

What might be the problem.

It first disappeared from the list. I went to the library tab, selected incomplete, highlighted the file, and resumed it.

This put it back in the download section with 0 length.

I am running 4.8.1

Cheers