Originally Posted by Mrs Beanbag
Also I really want to clarify this. On the Amiga horizontal scrolling isn't what causes sprites to disappear. Setting the horizontal display fetch 16 pixels earlier (further left) disables the last sprite because the bitplane data has to be read during the time it would otherwise have read that sprite's data. You can do scrolling without doing that but not if you want the screen to go right to the left-hand edge.
This only applies if you are using automatic mode sprites. If you manually load sprite 7's data with the copper at the left edge of the screen, you can still have all 8 sprites no problem.