dcc.Graph in dcc.Loading component isn't working right

[Marc-Andre-Rivet]

See #672 (comment)

This might be indicative of a deeper rendering problem within the loading component - why are we creating the graph twice?

[chriddyp]

Related #756. There have also been many community-reported issues:

• https://community.plotly.com/t/choroplethmapbox-hover-problem/33218/4
• https://community.plotly.com/t/dash-graph-showing-an-output-which-is-based-on-previous-iteration-of-input/36726/7