\Cref does not seem to be functioning properly. \usepackage{cleveref} (as is) is used.
\Cref{ref1}, \Cref{ref2} works but \Cref{ref1, ref2} results in only the first reference being shown, with the other as ??
Probably your problem is caused by the space inside your \Cref-command. Compare the output:
\documentclass{article}
\usepackage{cleveref}
\begin{document}
\begin{equation}\label{a}
1+1=2
\end{equation}
\begin{equation}\label{b}
2-1=1
\end{equation}
We used \Cref{a,b}.\\
We used \Cref{a, b}.
\end{document}
\documentclass{...}and ending with\end{document}. – Teepeemm Apr 01 '21 at 15:42\crefand friends do not allow whitespace in their arguments. If you change\Cref{ref1, ref2}to\Cref{ref1,ref2}, you'll do fine. – Mico Apr 01 '21 at 18:37