Why is a .txt file not visible on iPod Classic in its entirety once the iPod is disconnected from the desktop?

I have enabled my iPod Classic for disc use; and previously successfully transferred .txt files. The latest .txt file is fully visible on the iPod while the iPod is connected to the desktop, but once the iPod is disconnected only about 20% is visible. It is as though the wheel will rotate no further to reveal the rest. There is masses of free space on the iPod.