When using the arrow keys to select a disk image to transfer to the Apple, filenames are limited to 40 characters. If a filename has 41 or more characters it will not initiate transfer. It will "err out" and act like the directory from which you are selecting the file is empty.
In order to transfer a filename/image with more than 40 characters to the Apple I need to manually type in the name. Then it goes just fine.
Right, the file picker only keeps 40 characters (the width of the screen) around. Each file consumes exactly one line on screen. Anything longer than that is lost.