Minimal example:
\documentclass{memoir}
\usepackage{tabu}
\usepackage{threeparttable}
\begin{document}
\begin{table}
\begin{threeparttable}
\caption{Problematic table}
\label{tab:lf_mikrofone}
\begin{tabu} {l l}
Heading 1 & Heading 2 \\
\midrule
a\tnote{1} & b\tnote{2} \\
\bottomrule
\end{tabu}
\begin{tablenotes}
\item [1] qwerty
\item [2] asdf
\end{tablenotes}
\end{threeparttable}
\end{table}
\end{document}
This produces the expected output, but with an error:
Extra }, or forgotten \endgroup. \end{tabu}
If I change \begin{tabu} to \begin{tabular}, it works, but I would prefer tabu.
Exchanging \usepackage{threeparttable} for \usepackage{threeparttablex} makes no difference.
Can threeparttable and tabu be used together without errors?
