I’m trying to add two traces with their own Y-Axis but as soon as I add 2nd trace, the 1st one disappears! Here’s very easy repro of this issue:
In Jupyter Notebook:
import plotly
import plotly.graph_objs as go
t1=go.Scatter(x=[0, 1, 2], y=[0, 1, 8], mode='lines')
f2=go.FigureWidget([t1])
f2
First trace is drawn correctly. Now add 2nd trace with different Y-Axis:
t2=go.Scatter(x=[4, 5, 6], y=[0, 1, 2], mode='lines', yaxis='y2')
f2.add_trace(t2)
yaxis2 = {'title':'Y2', 'side':'right'}
f2.layout['yaxis2']=yaxis2
Notice the first trace goes away! If you didn’t set separate yaxis on 2nd trace then it works fine.
Possibly related issue.