Hello Steven,
Oh dear, the more I do the worse it gets! I have discovered that if I have Resize Images checked that I can load all five of the six images into the new gallery.
When I click on Customize I see one main image with six thumbnails (five plus one blank). I then click on Publish, with View in Browser checked, and click on Save. Nothing changes, no browser window open and when I check what is in the gallery file I can see config.xml and the images folder with just two images in it but no jbcore folder, nor thumbs folder.
If I try to open the gallery I am greeted with the message that the image file cannot be found four times, then the two which are found have blank thumbnails. Clicking on Customize shows the two main images but no thumbnails. :-(
However, when I publish only two of the five images are saved into the images folder and there is no jbcore nor thumbs folder.
This really doesn't make sense to me so I abandoned this new gallery, loaded up an existing one and added a few images to it. It all worked 100% correctly! I can only presume that there is a problem with one or two of the images that I was trying to use yesterday.
I then went back to the first six images and loaded four (all landscape, ignoring the portrait ones). Three loaded with the message about sizing for the fourth. With just these three images everything worked correctly. However, when I went to Open Gallery to try and add a different fourth image the gallery would not open. I tried another gallery, which did open correctly, so can only assume there must be something very wrong with the images that do not load.
I went back to scratch and started over again, loading one image at a time, and was able to load four normally, then a fifth with Resize Images checked but no matter what I tried I could not load the sixth, not as .jpg, .png nor .gif.