I tried using the syntax to render an image as follows:
![<alt_text>](data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAABy8AAANECAYAAAAJx2MrAAABYmlDQ1BJQ0MgUHJvZmlsZQAAKJFtkLFKw1AUhv9opKIVKoqDiGQRFarU...)
Testing the Markdown in Visual Code with Preview, the image renders correctly but in Workshop it seems the image source is not added in the HTML:
<img src alt="image">
Using a URL that links to an actual image, works. So it seems that the base64 style URL the only one that causes issues.