Plotting data only on secondary_y axes ignores subplot grid

Hello,

running the following code will produce a 2x2 subplot grid with data on the primary_y axes and data on one secondary_y axes.

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

rows = 2
cols = 2

fig = make_subplots(rows=rows, cols=cols, specs=[[{"secondary_y": True}] * cols] * rows)

fig.add_trace(go.Scatter(x=np.arange(5), y=np.arange(5), name='1:1 primary_y',),
              secondary_y=False, row=1, col=1)

fig.add_trace(go.Scatter(x=np.arange(5), y=np.arange(5), name=f'1:2 primary_y',),
              secondary_y=False, row=1, col=2)

fig.add_trace(go.Scatter(x=np.arange(5), y=np.arange(5), name=f'2:1 primary_y',),
              secondary_y=False, row=2, col=1)

fig.add_trace(go.Scatter(x=np.arange(5), y=np.arange(5), name=f'2:2 primary_y',),
              secondary_y=False, row=2, col=2)

# plot on secondary_y
fig.add_trace(go.Scatter(x=np.arange(5) + 1, y=np.arange(5), name=f'2:2 secondary_y',),
              secondary_y=True, row=2, col=2)

fig.update_layout(height=400, width=600)

fig.write_html('test_bug.html')

however if you don’t plot any data on a primary_y axes but leave the data on the secondary_y axes the height of the axes will take up the whole height of the figure

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

rows = 2
cols = 2

fig = make_subplots(rows=rows, cols=cols, specs=[[{"secondary_y": True}] * cols] * rows)

fig.add_trace(go.Scatter(x=np.arange(5), y=np.arange(5), name='1:1 primary_y',),
              secondary_y=False, row=1, col=1)

fig.add_trace(go.Scatter(x=np.arange(5), y=np.arange(5), name=f'1:2 primary_y',),
              secondary_y=False, row=1, col=2)

fig.add_trace(go.Scatter(x=np.arange(5), y=np.arange(5), name=f'2:1 primary_y',),
              secondary_y=False, row=2, col=1)

# fig.add_trace(go.Scatter(x=np.arange(5), y=np.arange(5), name=f'2:2 primary_y',),
#               secondary_y=False, row=2, col=2)

# plot on secondary_y
fig.add_trace(go.Scatter(x=np.arange(5) + 1, y=np.arange(5), name=f'2:2 secondary_y',),
              secondary_y=True, row=2, col=2)

fig.update_layout(height=400, width=600)

fig.write_html('test_bug.html')

is this behaviour intentional?

Reproduce the two examples using make_subplots, add_trace, and the secondary_y option, comparing the generated test_bug.html files. Investigate how the subplot grid assigns axis domains when the primary trace in row 2, column 2 is omitted. Done means secondary-only data remains confined to its 2x2 subplot cell rather than expanding across the figure.