The following example,
\documentclass{beamer}
\usetheme{Madrid}
\begin{document}
\begin{frame}
\begin{enumerate}[H1]
\item
\item[H2]
\end{enumerate}
\end{frame}
\end{document}
results (with all packages updated from CTAN) in a slide with a list where the second item is labeled "H2" (as expected), while the first item is labeled "H1", but in a smaller font and in a bullet. This has not been like this a year ago, and I assume it is not the intended behaviour of the enumerate package. Does anyone have an idea how I globally (I have a long document where I use enumerate a lot) could ensure that the enumerate package yields the same results as giving the label to the item command?