go.Bar zorder parameter ignored on Chart Studio

[alexhewson]

Issue
I am trying to produce a simple two trace horizontal bar chart, making use of the overlay barmode, which is uploaded to Chart Studio and then embeded on a website.

When my script is run to display offline with fig.show() my two traces appear in the desired order, respecting the zorder arguments that I've set. However, when uploaded to Chart Studio with py.plot(fig) the zorder parameter is ignored, hiding one of the traces.

Expected behaviour
zorder arguments should be respected, with the higher value being placed on top.

Code snippet

fig = go.Figure(
    go.Bar(
        x=[1, 2, 3],
        y=[0, 1, 2],
        orientation='h',
        zorder=1
    ),
)
fig.add_trace(
    go.Bar(
        x=[3, 4, 5],
        y=[0, 1, 2],
        orientation='h',
        zorder=0
    )
)

fig.update_layout(
    title_text=f"{plotly.__version__ = }",
    barmode='overlay',
    hovermode='closest')

py.plot(fig)

I'm developing in VS Code with jupyter notebook and a script, and both produce the same result.