We occasionally hear from authors that images are not working in their books, even though they are inserting them using the correct syntax in Markua.
We're not sure what causes this, but it appears that on occasion image files can become corrupted somehow.
Typically, this issue can be resolved by just saving a new version of the image, deleting the old image, and using the new image in its place.
How you do this will depend on the specific app you use for images, but typically it can be resolved with the following steps;
Double-click to open the image
Click "File" and then "Export" or "Save as" (or something similar)
Save a new version of the image in the same folder as the original image; you will have to give it a new name, e.g. by adding "copy" at the end of the filename
Delete the original image
Change the name of the new image to be the same name as the old image
The next time you create a preview, it should work.