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Rectangle shape not displayed in Safari

Hi,
I would like to ask you for a help.
Issue: Rectangle shape doesn’t show when starting the app. It comes only after refreshing the app.
Thanks a lot

OS: Big Sur 11.5
Browser: Safari
Python: 3.9
dash: 1.21.0
dash-bootstrap-components: 0.12.2
dash-core-components: 1.17.1
dash-html-components: 1.1.4
Plotly: 5.0.0


import pandas as pd
import dash
import dash_core_components as dcc
import dash_html_components as html
import dash_bootstrap_components as dbc
from dash.dependencies import Input, Output
import plotly.graph_objects as go
from plotly.subplots import make_subplots

checklist = dbc.Checklist(
    id='checklist',
    options=[
        {'label': 'Y1', 'value': 'Y1'},
        {'label': 'Y2', 'value': 'Y2'},
    ],
    value=['Y1'],
    inline=True,
)

iv_graph = dbc.Spinner(
    color="primary",
    children=[
              html.Div(
                  dcc.Graph(
                  id='graph',
                  )
              ),
              ]
)

app = dash.Dash(__name__, external_stylesheets=[dbc.themes.SKETCHY])

app.layout = dbc.Container(
    [
     dbc.Row([
              dbc.Col(checklist), 
              ]),
     dbc.Row([
              dbc.Col(iv_graph),
              ]),
    ],
)

#--------------graphs-------------------
@app.callback(
    Output('graph', 'figure'),
    Input('checklist', 'value'),
    )
def update_Graph_figure(checklist):

  data = [[3000, 80, 20],  [4000, 60, 30], [5000, 70, 10], [6000, 40, 50], [7000, 50, 30], [8000, 60, 40]]
  iv_ec = pd.DataFrame(data, columns = ['X', 'Y1', 'Y2'])
  
  fig = make_subplots(specs=[[{"secondary_y": True}]])
      
  if 'Y1' in checklist:
    fig.add_trace(go.Scatter(
          x=iv_ec["X"],
          y=iv_ec["Y1"],
          mode='lines',
          line_width = 4,
          marker_color='black',
          opacity=1),
          secondary_y=False,
    )
  if 'Y2' in checklist:
    fig.add_trace(go.Scatter(
        x=iv_ec["X"],
        y=iv_ec["Y2"],
        mode='lines',
        line_width = 2,
        marker_color='gray',
        opacity=1),
        secondary_y=False,
    )

  fig.add_vrect(
      x0=4000, x1=6000,
      line_width=0,
      fillcolor="red",
      opacity = 0.8,
  )

  return fig

if __name__ == "__main__":
  app.run_server(host='0.0.0.0', port='8050', debug=False,)