How to add an image to a font?

I was able to draw two lines and it showed when I installed it on my mac. But when I add an image it doesn’t seem to show, any ideas why?

In this screenshot, 0 and 1 works, but 2 doesnt

When adding an image like this, it acts as a background for you to draw your vector shapes on top of the image, using the image as a guide.
Only the vector shapes will show in the exported font.
Usuall you would add an image of a scanned letter there, where you have the dog, and then trace that scanned letter image with the path tool.
You cannot add an image in order to see that right away in the font.

You can export an image as part of an sbix font. But only few apps support sbix.