empty splom in case of two dimensions

Creating a splom with two dimensions, no diagonal and only the upper or lower half results in an empty figure.

Code that reproduces the issue:

import numpy as np
import pandas as pd
import plotly.graph_objects as go

data = pd.DataFrame({"col1": np.random.rand(10), "col2": np.random.rand(10)})

fig = go.Figure(
    go.Splom(
        dimensions=[{"label": label, "values": data[label]} for label in data.columns],
        diagonal={"visible": False},
        showupperhalf=False,
        showlowerhalf=True,
    ),
)


fig.write_html("test.html")  # or fig.show()
# Gives me an empty plot. Setting `diagonal` or `showupperhalf` to `True` does give a plot

Expected result
A single scatter plot.

Start with the go.Splom reproduction in the issue, especially the two dimensions, hidden diagonal, and lower-half-only settings. Run the script with fig.show() or fig.write_html() and trace the generated figure behavior. Done means the two-dimensional lower-half-only splom renders its single scatter plot instead of an empty figure.