The following MWE tries to display two characters from the STIX fonts (U+1D61F and U+2047).
Both are listed in
https://github.com/stipub/stixfonts/blob/master/docs/STIXTwoMath-Regular.pdf
One of them displays, the other doesn't.
Why is that, and how to get around it?
MWE:
\documentclass[a4paper, 11pt, oneside, final]{article}
\usepackage{unicode-math}
\setmathfontface\StixTwoMath{STIX Two Math}
\usepackage[autostyle]{csquotes}
% Mathematical Alphanumeric Symbols.
\NewDocumentCommand\BCon{}{{\ensuremath{\StixTwoMath{\char"1D61F}}}}
% General Punctuation.
\NewDocumentCommand\BNc{}{{\ensuremath{\StixTwoMath{\char"2047}}}}
\NewDocumentCommand\BNq{}{{\ensuremath{\StixTwoMath{\Question}}}}
\begin{document}
\BCon{}: The \enquote{\BCon{} signifies a double.}
\BNc{}: The \enquote{\BNc{} signifies an arbitrary bid.}
\BNq{}: The \enquote{\BNq{} signifies an arbitrary bid.}
\end{document}

Missing character: There is no ⁇ (U+2047) in font [latinmodern-math.otf]:modeyou are using latin moder math – David Carlisle Oct 29 '22 at 17:46\sffamily) it does nothing in math, also you accessed the character via\charwhich is mainly for text so would have worked if you had not used\ensuremathbut as you loadunicode-mathI suspect you want to use\setmathfontto load stix two math – David Carlisle Oct 29 '22 at 19:54