[BUG]: Unable to `write_image` with `datetime64` axis in recent versions

[EuanRichard]

Description

With plotly==6.3.1 and kaleido==1.1.0, I wasn't able to add shapes (add_vline, add_shape, ...) to a time-axis line plot and then use write_image. The shapes wouldn't appear on the image, or would have a wildly incorrect x-axis location.

Steps to reproduce

import pandas as pd
import plotly.express as px

x = ['2001-01-01', '2001-01-02', '2001-01-03']
y = [0, 3, 1]

x = pd.to_datetime(x) # Now Pandas Index of NumPy datetime64[ns]

fig = px.line(x=x, y=y)

fig.add_vline('2001-01-02')
fig.add_shape(type='rect', x0='2001-01-01', x1='2001-01-01 12:00:00', y0=0, y1=1)

fig.show() or fig.write_html() works fine:

fig.write_image() with .png, .svg etc. does not:

Notes

• Downgrading to plotly==6.0 and kaleido==0.2.1 will cause write_image to work OK, so maybe a recent change.
• Removing the line pd.to_datetime(x) will also "fix" the issue, so maybe related to handling of datetime64[ns] inside write_image (as can be seen in the lower plot, it doesn't seem to recognise the x-axis as a time axis)?