I'm trying to use the result from a fill between as a legend entry, but I can't get it to work:
\documentclass{article}
\usepackage{tikz}
\usepackage{pgfplots}
\usepgfplotslibrary{fillbetween}
\begin{document}
\begin{figure}
\begin{tikzpicture}
\begin{axis}
\addplot[name path = upper, draw = none] {5 + rand};
\addplot[name path = lower, draw = none] {-5 + rand};
\addplot[black!10, area legend] fill between[of = upper and lower];
\addlegendentry{My interval}
\end{axis}
\end{tikzpicture}
\end{figure}
\end{document}
gives

with a line in the legend image instead of the rectangle I expected from using area legend in the options to \addplot.
I tried providing a legend image manually using
\addlegendimage{\draw[fill = black!10] (0cm, -0.1cm) rectangle (0.6cm, 0.1cm)}
but that did nothing. (The \draw code is inspired by Section 4.9.5 in the pgfplots manual and is supposed to be the default appearance of a area legend entry.)
Any ideas? Thanks in advance.
Edit:
Adding area legend to the axis option gets me halfway there, but the fill is still not right.


pgfplotsmanual shows an example of this "just working" on p. 382 (v1.12) with no special handling. – Paul Gessler May 23 '15 at 21:17