Excel is kinda funky with images. Technically, a cell cannot contain an image. Excel gets around this by providing various pasting and positioning options to make it appear as if an image is in a cell. In reality an image is at best, aligned, sized, and locked to a cell. It isn't actually the cell contents. This can be seen by pasting an image into a cell that already contains a value which is acted upon by a formula. Even though the cell appears to be an image, the value continues to function properly in the formula thus proving it is still the real cell contents. Resizing column width will also often show an image isn't actually in the cell.
Bill is spot on. Distribute as PDF when all finished and avoid all the Excel quirkiness (not meant in a bad way, but you have to admit Excel has its fair share of unique operations).
