Incompatible behavior for filling area with `Scattergl` compared to `Scatter`

[erezinman]

Hi, following this example on the website, if I replace all the Scatter traces with Scattergl, the error-band is not shown.

That is, using the following code (only change is that I use webgl):

import plotly.graph_objs as go
import pandas as pd

df = pd.read_csv('https://raw.githubusercontent.com/plotly/datasets/master/wind_speed_laurel_nebraska.csv')

fig = go.Figure([
    go.Scattergl(
        name='Measurement',
        x=df['Time'],
        y=df['10 Min Sampled Avg'],
        mode='lines',
        line=dict(color='rgb(31, 119, 180)'),
    ),
    go.Scattergl(
        name='Upper Bound',
        x=df['Time'],
        y=df['10 Min Sampled Avg']+df['10 Min Std Dev'],
        mode='lines',
        marker=dict(color="#444"),
        line=dict(width=0),
        showlegend=False
    ),
    go.Scattergl(
        name='Lower Bound',
        x=df['Time'],
        y=df['10 Min Sampled Avg']-df['10 Min Std Dev'],
        marker=dict(color="#444"),
        line=dict(width=0),
        mode='lines',
        fillcolor='rgba(68, 68, 68, 0.3)',
        fill='tonexty',
        showlegend=False
    )
])
fig.update_layout(
    yaxis_title='Wind speed (m/s)',
    title='Continuous, variable value error bars',
    hovermode="x"
)
fig.show()

It does work (for some reason) if and only if I reorder the scatter plots ([measurement, upper, lower] -> [upper, lower, measurement]) and I add fill='tonexty' to both the upper and lower traces.

That is:

import plotly.graph_objs as go
import pandas as pd

df = pd.read_csv('https://raw.githubusercontent.com/plotly/datasets/master/wind_speed_laurel_nebraska.csv')

fig = go.Figure([
    go.Scattergl(
        name='Upper Bound',
        x=df['Time'],
        y=df['10 Min Sampled Avg']+df['10 Min Std Dev'],
        mode='lines',
        marker=dict(color="#444"),
        fill='tonexty',
        line=dict(width=0),
        showlegend=False
    ),
    go.Scattergl(
        name='Lower Bound',
        x=df['Time'],
        y=df['10 Min Sampled Avg']-df['10 Min Std Dev'],
        marker=dict(color="#444"),
        line=dict(width=0),
        mode='lines',
        fillcolor='rgba(68, 68, 68, 0.3)',
        fill='tonexty',
        showlegend=False
    ),
    go.Scattergl(
        name='Measurement',
        x=df['Time'],
        y=df['10 Min Sampled Avg'],
        mode='lines',
        line=dict(color='rgb(31, 119, 180)'),
    ),
])
fig.update_layout(
    yaxis_title='Wind speed (m/s)',
    title='Continuous, variable value error bars',
    hovermode="x"
)
fig.show()

[erezinman]

This happens in version 4.14.3

[maegul]

Just saw this ... seems to be a duplicate of or related to my own issue from a few months ago: #3194 ... FYI