<p>It's the fonts! I was able to replicate after I uninstalled <a href="https://developer.mozilla.org/@api/deki/files/4719/=STIX-mozilla1.9.zip" rel="nofollow">these</a>. Hence installing the fonts renders the formula correctly.</p>

<p>Via <a href="https://developer.mozilla.org/en/Mozilla_MathML_Project/Fonts" rel="nofollow">https://developer.mozilla.org/en/Mozilla_MathML_Project/Fonts</a></p>
