Text alignment between columns (beamer)

Question

I have a slide with two column in beamer, with overlays in both columns.

In the left column, I have a list of three items ; each item appears at each mouseclick/overlay and then stays on the screen.

In the right column, the content varies at each mouseclick/overlay along with the left column : at first and second times there are lists, and on the third one there is a figure.

My issue is that the content in the left column "moves" according to the content of the right column ; how can I fix this content at a particular place on the slide ?

Here is what my code looks like (It's the first time I'm using overlays, maybe it's a bit ugly, sorry) :

\begin{frame}{MyTitle}
\begin{columns}[t]
    \begin{column}{6cm}
        \begin{itemize}
            \only<1-> { \item item 1 (left column, step 1)}
            \only<2-> { \item item 2 (left column, step 2)}
            \only<3-> { \item item 3 (left column, step 3)}
        \end{itemize}
    \end{column}
    \begin{column}{6cm}            
        \only <1> {
        \begin{itemize}
            \item item 1 (right column, step 1)
            \item item 2 (right column, step 1)
            \item item 3 (right column, step 1)
        \end{itemize}
        }
        \only<2> {
        \begin{itemize}
            \item (right column, step 2)
            \item (right column, step 2)
        \end{itemize}
        }
        \only<3> {
        \begin{figure}
            \centering
            \includegraphics[scale=0.25]{left_column_step_3.png}
        \end{figure}
        }
    \end{column}
\end{columns}
\end{frame}

Answer 1

A simple way to circumvent this problem is to use a top aligned frame:

\documentclass{beamer}

\begin{document}

\begin{frame}[t]{MyTitle}
\begin{columns}[t]
    \begin{column}{.48\textwidth}
        \begin{itemize}[<+->]
           \item item 1 (left column, step 1)
           \item item 2 (left column, step 2)
           \item item 3 (left column, step 3)
        \end{itemize}
    \end{column}
    \begin{column}{.48\textwidth}            
        \only<1>{
            \begin{itemize}
                \item item 1 (right column, step 1)
                \item item 2 (right column, step 1)
                \item item 3 (right column, step 1)
            \end{itemize}
        }
        \only<2>{
            \begin{itemize}
                \item (right column, step 2)
                \item (right column, step 2)
            \end{itemize}
        }
        \includegraphics<3>[width=\textwidth]{example-image}
    \end{column}
\end{columns}
\end{frame}


\end{document}