Bug display subplots with an only one secondary y axis

📊 Plotly Python
1

Hi, I figured out that rendering a figure with subplots and with at least one subplot with only a secondary y axis and not a primary one, it creates a display bug. Here’s a code reproducing it :

import plotly.graph_objects as go
from plotly.subplots import make_subplots

# Create subplots: 1 column, 3 rows, with the second subplot having a secondary y-axis
fig = make_subplots(
    rows=3, cols=1,
    shared_xaxes=True,
    vertical_spacing=0.1,
    subplot_titles=("Primary Y-Axis Plot", "Secondary Y-Axis Plot", "Another Primary Y-Axis Plot"),
    specs=[[{}], [{'secondary_y': True}], [{}]]  # Define the secondary_y for the second subplot
)

# Add first plot (e.g., scatter plot)
fig.add_trace(
    go.Scatter(x=[1, 2, 3], y=[4, 5, 6], mode='lines+markers', name='Scatter 1'),
    row=1, col=1
)

fig.add_trace(
    go.Scatter(x=['A', 'B', 'C'], y=[10, 20, 30], mode='lines', name='Line 1'),
    row=2, col=1,
    secondary_y=True  # secondary y-axis
)

# Add third plot (e.g., line plot)
fig.add_trace(
    go.Scatter(x=[1, 2, 3], y=[2, 4, 8], mode='lines', name='Line 2'),
    row=3, col=1
)

# Update layout
fig.update_layout(
    height=800,
    width=600,
    title_text="Subplots with Secondary Y-Axis",
    showlegend=True
)

# Update y-axis titles for secondary y-axis subplot
fig.update_yaxes(title_text="Primary Y-Axis", row=2, col=1)
fig.update_yaxes(title_text="Secondary Y-Axis", row=2, col=1, secondary_y=True)

fig.show()