<svg width="800" height="128" xmlns="http://www.w3.org/2000/svg">
<defs>
<filter id="testFilter" filterUnits="objectBoundingBox" x="0%" y="0%" width="100%" height="100%" >
<feConvolveMatrix order="3 8" kernelMatrix="0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0" targetY="7" preserveAlpha="true" />
</filter>
</defs>
<!-- Both shapes should look identical -->
<!-- Expected -->
<rect x="0" y="0" width="800" height="48" fill="#0000FF" />
<g>
<rect x="0" y="16" width="800" height="16" fill="#00FF00" />
</g>
<!-- Actual -->
<rect x="0" y="80" width="800" height="48" fill="#0000FF" />
<g filter="url(#testFilter)">
<rect x="0" y="96" width="800" height="16" fill="#00FF00" />
</g>
</svg>