Below is a minimal example that displays my problem. In the top row I have an \onslide<+-> command that seems to introduce an extra vertical space in the table, which is not there (as desired) in the second row, when this command is not present. Why is this happening, and how can I remove the extra vertical space?
\documentclass{beamer}
\usepackage{tabularx}
\begin{document}
\begin{frame}{Minimal Example}
\begin{tabularx}{0.9\textwidth}{p{0.18\textwidth}|p{0.32\textwidth}|X}\hline
left & middle & \onslide<+-|handout:0>{right}\\\hline
left & middle & right\\\hline
\end{tabularx}
\end{frame}
\end{document}