Bar charts don't group when there's only 1 group

import plotly.graph_objects as go
import pandas as pd
import datetime

data = [
    {"date": datetime.date(2025,7,20), "net_sales": 23.34, "gross_sales": 32.98},
    {"date": datetime.date(2025,7,21), "net_sales": 45.21, "gross_sales": 68.12},
    {"date": datetime.date(2025,7,22), "net_sales": 12.98, "gross_sales": 34.54},
    {"date": datetime.date(2025,7,23), "net_sales": 41.32, "gross_sales": 45.32},
]

df = pd.DataFrame.from_records(data)

def make_figure(df, width=None):
    fig = go.Figure()
    fig.add_trace(go.Bar(
        x=df['date'],
        y=df['gross_sales'],
        xperiod=24*60*60*1000,
        xperiod0=df['date'].min(),
        xperiodalignment="middle",
        width=24*60*60*1000 * 0.4,
        opacity=0.6,
        offsetgroup='gross'  # same behaviour exhibited whether or not this is specified
    ))
    fig.add_trace(go.Bar(
        x=df['date'],
        y=df['net_sales'],
        xperiod=24*60*60*1000,
        xperiod0=df['date'].min(),
        xperiodalignment="middle",
        width=24*60*60*1000 * 0.4,
        opacity=0.6,
        offsetgroup='net'  # same behaviour exhibited whether or not this is specified
    ))
    fig.update_layout(
        barmode='group',
        xaxis={
            'ticklabelmode': 'period',
            'tickmode': 'auto',
            'dtick': 24*60*60*1000,
            'range': (df['date'].min(), df['date'].max() + datetime.timedelta(days=1)),
        })
    fig.show(renderer="browser")

make_figure(df)
make_figure(df[0:1])