Scattermapbox maki symbols plot on map, but not legend

Hi Plotly,

First, thank you for all the fantastic work you do.

I am a big fan of / heavy user of the plotly.go objects that render maps (Scattermapbox / Choroplethmapbox).

I have noticed, however, that when setting the symbol type to a maki symbol, it will render it on the map - but not the legend. This feels like a bug, as there is also a colour associated with the legend item that is not matched anywhere on the plot / by the symbol (except in hovertext).

Reproducible example below:

import os
import plotly.graph_objects as go

mapboxt = os.getenv('MAPBOX_TOKEN') # a mapbox token

lats = [52.370216, 53.2191696,  50.851368, 51.8125626]
lons = [4.895168,  6.5666699, 5.690973, 5.8372264 ]

fig = go.Figure()

scatt = go.Scattermapbox(
            lat=lats,
            lon=lons,
            mode='markers',
            hovertext=['Amsterdam', 'Groningen',  'Maastricht', 'Nijmegen'],  
            hoverinfo='text',                 
            below='',                 
            marker=dict(symbol ='hospital'),
            name ='my_fake_hospitals',
            showlegend=True)

fig.add_trace(scatt)

fig.update_layout(go.Layout(title_text ='Is it a hospital? No, it is a blue dot!', 
                            title_x=0.5, 
                            width=750, 
                            height=700,
                            mapbox = dict(center= dict(lat=52.370216, lon=4.895168),            
                                         accesstoken= mapboxt,
                                         zoom=5,
                                         style="light"
                                       )))

fig

Finally, as a side note, some maki symbols plot whilst others do not. I have determined through trial and error that this is down to whether or not the MapBox style includes these specific symbol types. Using custom Mapbox styles, therefore, may silently break the maki functionality as well.

Thanks you for your attention.

首先运行提供的、使用 Scattermapbox、Maki 符号 "hospital" 和 showlegend=True 的 Python 可复现示例，然后将地图符号与其图例项进行比较。跟踪 Scattermapbox 对 marker-symbol 和图例的处理，包括关于 Mapbox 样式的注释；当受支持的 Maki 符号在图例和地图中一致显示，并且该行为由回归测试覆盖时，即表示完成。