PDF.JS Express Merge API and SVG causes "Draft" stamp on exported doc

Detailed description of issue
When merging annotations through the PDF.JS Express API - it works fine if the annotations added to the document is PNG images. However, when adding an SVG like the one below it appears fine while editing the document, however exporting the document results in a “Draft” box to be drawn over the spot where annotation is supposed to be. Please see link to exported PDF as example as well as the SVG graphic added as an annotation.

Exported PDF Example: http://www.ernic.co.za/f8e14be8-94d1-ee09-1b9b-d8b5c5a78acb.pdf

SVG Annotation Stamp:

image/svg+xml;base64,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

Expected behaviour
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Link to document
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Code snippet
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Hey there,

Unfortunately Express does not support flattening SVG stamps. We are able to display them in the viewer, but they cannot be flattened.

To make the flattening work you would have to convert it to either a PNG or JPEG. Luckily there are several ways to do this on the client using the HTML5 canvas APIs.

If you have any further questions please let me know.

Thanks!
Logan