TikZ matrix fails inside makebox or framebox

Here you have three different solutions.

The first one uses background library to draw the background rectangle associated to any tikzpicture.

The second draw the matrix node without drawing inner matrix nodes. It's possible to use this solution because you draw a matrix. With any other figure you should use previous solution.

And the third uses a tcbox (from tcolorbox). It's similar to fbox but with more configuration options. In this case you have to use ampersand replacement option into the matrix text.

\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{matrix, backgrounds}
\usepackage{tcolorbox}
\begin{document}

  \begin{tikzpicture}[show background rectangle]
    \matrix (m) [matrix of nodes] { 
      text & text \\
    };
  \end{tikzpicture}%

  \begin{tikzpicture}%[show background rectangle]
    \matrix (m) [draw, matrix of nodes] { 
      text & text \\
    };
  \end{tikzpicture}%

    \tcbox[sharp corners, colback=white, size=fbox]{\begin{tikzpicture}
    \matrix (m) [matrix of nodes, ampersand replacement=\&] { 
      text \& text \\
    };
  \end{tikzpicture}}

\end{document}

I found option ampersand replacement=\& (as follows) will solve the problem.

\matrix (m) [matrix of nodes,ampersand replacement=\&] { 
  text \& text \\
};

Though I would still appreciate if someone can explain why & causes troubles insides \makebox.

\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{matrix,positioning,fit}

\begin{document}
%   \makebox{%
        \begin{tikzpicture}
            \matrix (m) [matrix of nodes] { 
                text & text \\
            };
        \node[draw,fit=(m-1-1) (m-1-2),inner sep=0pt]{};
        \end{tikzpicture}%
%   }
\end{document}