Saving a customized Layout with graphics is not possible

We want to save a custom layout (HTML) with an embedded graphic.
The layout is saved, but when reopening it, the graphic disappears.

Please try it yourself: click on "new mail", insert a graphic (jpg or png) on top of the HTML Mail, save it as an new layout.
Open it and you will see an empty layout.

I think, this is not working as designed. Am I wrong ?

regards,
Stefan