Just imagine me walking out of a cave and hollering that into the void, just like Chris Elliot in Cabin Boy. But they are indeed not functioning at 100%. Apparently, there is a 100 character limit for filenames on Neocities. This isn’t just limited to the filename, either, as noted on this issue on github. When Hugo Shortcode Gallery does its behind the scenes magic (making thumbnails and the like) it generates these filenames that are fairly long. These get rejected when trying to upload through the neocities CLI. So thumbnails are broken until further notice.
I might play aroudnd with hugo easy gallery though this isn’t being actively developed which is what turned me away from it to begin with. Maybe Neocities will take notice and up the character limit to something more in-line with operating system standards. Or maybe they won’t!