Marker icon on plotly scattermapbox not updating

I am using plotly’s scattermapbox to render a map and trying to change the symbol. I have been using circle for point coordinates and need to update to a marker symbol instead. When i update the symbox in the code, the map defaults to circle.


                        "type": "scattermapbox",
                        "lat": df['Lat'],
                        "lon": df['Long'],
                        "name": "Location",
                        #"hovertext": rent,
                        "showlegend": False,
                        "hoverinfo": "text",
                        "mode": "markers",
                        "customdata": df.loc[:,cd_cols].values,
                        "marker": {
                            "symbol": "marker",  | defaults to circle
                           # "size": 18,
                            "opacity": 0.8,
                            #"color": "black"

marker is a valid symbox based on the documentation here: