I updated the NextGen Gallery plugin to 1.9.2 from 1.9.0 for a client of mine and now the Gallery thumbnails in Manage Gallery do not show, before the update these were showing.
My quick solution because I thought it may of been to do with my client using spaces in the image filenames involved deleting an image and and re-uploading it without spaces in the filename. However due to the large amount of images (500+) all with different meta info my client doesn't want to do this.
Is there another way I could go about fixing this issue? Apart from downgrading back to 1.9.0, I was thinking maybe there is a way to edit the thumbnail script so that it replaces spaces with a %20 instead of deleting them entirely on the thumb.