NextGen Gallery will not sort

I cannot sort my newest gallery. I am going to “Manage Galleries”, then find the newest one, click on “Sort Gallery”, edit the order (it’s actually just by file name), make sure it shows in the order I want, then hit “Update Sort Order”. However, I then go back to the gallery page and the order is not changed at all. I am no able to change the picture order at all. Please help.
BTW I originally added the gallery with a shortcut but have now also tried adding it with the “green box” and then sorting in the popup window. Same result.
The gallery is here: http://www.biggster.com/mygallery/wapta-traverse-2016/
You can see from the picture titles that it is showing in exactly reverse order.