Re: IIIDownloader and Imagefap
After much experimenting I have verified that this problem isn't machine specific. It persists across three different computers, running three different versions of Windows (Vista, Win 7 and Win 10).
Most of the time galleries won't add to the waiting queue. After multiple attempts at dragging an dropping them they do - sometimes on the first try, sometimes it takes 10 or more tries. Once they have been added to the queue, they download just fine.