So believe it or not, it is a specific letter of the papyrus font. It is the capital N produces an unsliceable file. I validated the XML (it’s really, really simple with just one letter on screen, I could hand validate it for that matter). Now I emailed @rita who suggested trying the “Save As” rather than “Export” in AI. Yep, the save-as one works fine, the export does not, and only when an N is on the screen does this make a difference! So in looking (and diffing) the XML of the SVGs it appears to be a line wrap issue? I will let @Rita figure out why this causes a problem in slicing.
for anyone who cares here is the bad one (export as):
<svg id="Layer_1" data-name="Layer 1" xmlns="http://www.w3.org/2000/svg" width="20in" height="12in" viewBox="0 0 1440 864">
<defs>
<style>
.cls-1 {
fill: #006838;
}
</style>
</defs>
<title>n</title>
<path class="cls-1" d="M729.87,426.74a.83.83,0,0,1-.43.37,3.14,3.14,0,0,1,.27.72l-.08,1.6.08,1.27-.23.92.08,1.29-.12,1.8.12,1-.12.68.08,1.84,0,.53-.12-.2q-.33.25-.33.47,0,.39.57.76a5.36,5.36,0,0,1,.16,1.07,3.64,3.64,0,0,1-.3,1.47,15.38,15.38,0,0,1-1.1,1.94l-.27.43-.76.45-.16-.45-.92-1.41-1.17-1.46-.88-1.52-.31-.41.08-.43q0-.47-.68-1a9,9,0,0,1-1.07-1l-1.07-1.91-.57-.68-.35-1a1.24,1.24,0,0,0-1.25-.8l-.23-.47-1.13-1.86-.31-1-.64-.72-.12.16-.31-.2a7.46,7.46,0,0,0-2.56-2.91,2.66,2.66,0,0,0,.16-.72q0-.49-.37-.49l-.43.16a.85.85,0,0,0-.53-.31l-.39.2.43.92L712,426l.12.31-.16.84.08,1.68-.12.57-.33.16,0,.47.33,1.13,0,0v0a2,2,0,0,1-.49,1l.16.8.18.45v5.74l.23,1.68v0a.33.33,0,0,1,0,.1l-.23,1.11,0,.23c.23.13.35.28.35.45a6.07,6.07,0,0,1-1,1.64l-.23.35-.45,0c-.25.3-.45.45-.61.45h0l-.43,0-.33.08,0-.49a1.83,1.83,0,0,1,.18-.72l.43-.55.33-.49-.45-.39.12-.45.23-.57a4.67,4.67,0,0,1-.2-.66l0-.07a.21.21,0,0,0,0-.07l.29-1-.1-2.25a.9.9,0,0,1,.61-.39V437l-.43-.53.08-.43-.08-.41.12-1.11a.08.08,0,0,0,0,0l0,0-.25-.84.14-1.13-.08-.8q0-.39.55-.76l0-.47-.27-.64a2.06,2.06,0,0,1,.12-.57.82.82,0,0,1-.35-.62,5.44,5.44,0,0,1,.23-1.21l-.2-.27,0-.57-.18-1.35a2,2,0,0,1,.18-.57v-.45a2.94,2.94,0,0,0-.21-1.46l-.88-1.09.16-.43.49-.29a4.08,4.08,0,0,0,.68-.45,1.21,1.21,0,0,0,.31-.51l.33-.2.92-1.07a.32.32,0,0,1,.23-.08.75.75,0,0,1,.68.55l.88,1.72.35.45.33.61-.12.12a9.64,9.64,0,0,1,1.23,1.76l1,1.68a2.89,2.89,0,0,1,.33.68.63.63,0,0,1-.18.43l.8.45-.12.35.33.41.8,1.15.59.57.21.64,1.76,1.88-.37.2a1,1,0,0,0,.25.52,1.45,1.45,0,0,0,.63.21l.92,1.27-.27,0,.53.37a3,3,0,0,1,.7.63,1.73,1.73,0,0,1,.21.74l.27.27,0,.27a1.89,1.89,0,0,0,.27.92l.45.29a5.47,5.47,0,0,1,.88.43l.84,1.29.43.27.57.49.2-.45,0-2.36.41-1a1.2,1.2,0,0,1-.41-.76.66.66,0,0,1,0-.27l.25-.8.12-2.79.31-.61-.23-.61.16-.92v0c0-.17-.16-.32-.47-.45l-.1-5.08a.46.46,0,0,0,.36-.15,1.24,1.24,0,0,0,.13-.52l-.61-.45-.08-.68a3.73,3.73,0,0,0-.24-1.13.61.61,0,0,0-.6-.27,2.15,2.15,0,0,1-.08-.47q0-.72,1.68-1.15a2.43,2.43,0,0,1,.48-.57,5,5,0,0,1,.89-.45,1.43,1.43,0,0,1,.23.72l-.08.57.12.43,0,.76,0,1.64a2.67,2.67,0,0,1-.12.84l-.16.8v0l.31,1.29-.08,1Z"/>
</svg>
Here is the good one (save as):
<?xml version="1.0" encoding="utf-8"?>
<!-- Generator: Adobe Illustrator 21.1.0, SVG Export Plug-In . SVG Version: 6.00 Build 0) -->
<svg version="1.1" id="Layer_1" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" x="0px" y="0px"
width="1440px" height="864px" viewBox="0 0 1440 864" style="enable-background:new 0 0 1440 864;" xml:space="preserve">
<style type="text/css">
.st0{fill:#006838;}
</style>
<g>
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l0.1,1l-0.1,0.7l0.1,1.8l0,0.5l-0.1-0.2c-0.2,0.2-0.3,0.3-0.3,0.5c0,0.3,0.2,0.5,0.6,0.8c0.1,0.5,0.2,0.8,0.2,1.1
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l-0.2,0.8v0l0.3,1.3l-0.1,1L729.9,426.7z"/>
</g>
</svg>