Tikz-cd

I’m having difficulty rendering latex tikz-cd diagrams. Could anyone help?

I feel like this should work:


\usepackage{tikz-cd}

\begin{document}

\begin{tikzcd}

A \arrow[rd, "f"] & B

\end{tikzcd}

\end{document}

But it’s not rendering.

I copied and pasted the code example from here:

And that code renders perfectly. I am wondering if the problem is the body of the diagram rather than any of the latex headers?