add_vline fails with datetime64[ns]

[CarlAndersson]

When using datetime64 from numpy with nanosecond precision, the add_vline method does not show any vlines.

Reproducible as follows:

import plotly.graph_objects as go
import numpy as np

t = np.arange(120).astype("timedelta64[s]") + np.datetime64("2025-01-14 08:00")
t = t.astype("datetime64[ns]")
y = np.linspace(0, 1, t.size)
fig = go.Figure()
fig.add_scatter(x=t, y=y)
fig.add_vline(x=t[5])

• Removing the conversion to "datetime64[ns]" makes the vline appear.
• Converting to "h", "m", "s", "ms" or "us" all seem to work. (The time spacing have to be modified for hours or minutes.)
• Converting only the time input to add_vline also resolves the problem.