Dash stuck on "Loading...."

Hello,

I am trying to get a scattermapbox rendered following the example here. I believe I’m performing the actions necessary, but it seems to hang on the “Loading…” page. I create a small example in python below:

import dash
import json
import dash_core_components as dcc
import dash_html_components as html
import pandas as pd
import geopandas as gpd


# public token
mapbox_access_token = 'pk.eyJ1IjoiYWpzNTEyMTAiLCJhIjoiY2pubTF0bmd0MW1xZDNrcG11MzFtcmRkMyJ9.VV44hkCsoc8ZcKYbH9wfbA'

app = dash.Dash(__name__)

gdf  = gpd.read_file( 'https://raw.githubusercontent.com/TNRIS/tx.geojson/master/counties/tx_counties.geojson' )

app.layout = html.Div( [ dcc.Graph(
	id = 'TxWCD-choropleth',
	figure = dict(
		data = [dict(
			type = 'scattermapbox'
		)],
		layout = dict(
			height   = 900,
			autosize = True,
			mapbox 	 = dict(
				layers =[dict(

					sourcetype = 'geojson',
					type 	   = 'fill',
					color	   = '#265465',
					source     = json.loads( gdf.to_json() )
				)],
				accesstoken = mapbox_access_token,
				center  = dict(
		            lat = 31.3,
		            lon = -99.2
		        ),
		        zoom = 5.2,
		        style='light'
			)
		)
	)
)])


if __name__ == '__main__':
    app.run_server( port = 8051, debug = True )

weirdly if I change the geopandas object to instead read https://raw.githubusercontent.com/TNRIS/tx.geojson/master/tx.geojson it works, but is slow. I wonder if it has something to do with the data size. I was running it before and it worked fine, this just started happening once I updated some packages on pip. Any help would be greatly appreciated.

Thanks!