Strange behavior of gridlines when sharing multiindex axis across subplots

When running the code below, the gridline between items of the first level of the y-axis has strange behavior. The divider extends only to a certain part of the graph, leaving the rest of the graph without any dividers between the items.

Any ideas on how to fix this?

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

# MultiIndex
ylabels = [
    ['Group 1', 'Group 1', 'Group 2', 'Group 2'],
    ['Subgroup A', 'Subgroup B', 'Subgroup A', 'Subgroup B']

# Create subplots with a shared y-axis
fig = make_subplots(rows=1, cols=3, shared_yaxes=True)

# First subplot
fig.add_trace(go.Bar(y=ylabels, x=[5, 15, 25, 35], orientation='h'), row=1, col=1)
fig.add_trace(go.Bar(y=ylabels, x=[1, 2, 3, 4], orientation='h'), row=1, col=1)

# Second subplot
fig.add_trace(go.Bar(y=ylabels, x=[45, 55, 65, 75], orientation='h'), row=1, col=2)
fig.add_trace(go.Bar(y=ylabels, x=[5, 6, 7, 8], orientation='h'), row=1, col=2)

# Third subplot
fig.add_trace(go.Bar(y=ylabels, x=[85, 95, 105, 115], orientation='h'), row=1, col=3)
fig.add_trace(go.Bar(y=ylabels, x=[9, 10, 11, 12], orientation='h'), row=1, col=3)

# Update layout properties
fig.update_layout(title='Subplots with Shared Y-Axis and MultiIndex Data', showlegend = False)

# Show the plot

Hey @welcoem to the forums and thanks for the example.

I’ve never seen this nor would I know to fix this right now out of my head. Might even be a bug.