How to fix Plotly Python putting a bar chart in front of trace lines.

I'm posting this in case it helps anyone else. It caused me 4 hours of horrible frustration.

I'm trying draw a quite hideously over complicated set of graphs which I've cobbled together in truly apocalyptically bad spaghetti code in Python. But it kinda works.

And then I added a bar graph that I needed to go behind the lines. This is what happened.

One day I'll share more of the full graphs, suffice it to say they're being prepared for our next #cryptoclassaction court date in March.

This particular graph has two subplots one above the other with 4 y-axis, 2 on each subplot.

I reduced my problem to a much simpler example:

The code for which looks like this:

import plotly.graph_objects as go 
from plotly.subplots import make_subplots 
 
fig = go.Figure() 
 
fig.add_trace( 
    go.Bar( 
        x=[0, 1, 2, 3, 4, 5], 
        y=[1.5, 1, 1.3, 0.7, 0.8, 0.9], 
        marker_color='blue' 
        ) 
    ) 
 
fig.add_trace( 
    go.Scatter( 
        x=[0, 1, 2, 3, 4, 5], 
        y=[1.5, 0.3, 1.2, 0.5, 0.3, 0.9], 
        line = dict( 
            width=20, 
            color='yellow' 
            ), 
        ) 
    ) 
fig.show() 

So far so good. Then I converted this to a plot with subplots and separate y-axis and mimicked what I did with my complex plot: I ADDED the bar graph and created a secondary y-axis for it. Here's the graph I got and the code:

import plotly.graph_objects as go 
from plotly.subplots import make_subplots 
 
# fig = go.Figure() 
fig = make_subplots(rows=1, cols=1, 
                      specs=[[{"secondary_y": True}]]) 
 
fig.add_trace( 
    go.Bar( 
        x=[0, 1, 2, 3, 4, 5], 
        y=[1.5, 1, 1.3, 0.7, 0.8, 0.9], 
        marker_color='blue' 
        ), 
    row = 1, 
    col = 1, 
    secondary_y = True 
    ) 
 
 
fig.add_trace( 
    go.Scatter( 
        x=[0, 1, 2, 3, 4, 5], 
        y=[1.5, 0.3, 1.2, 0.5, 0.3, 0.9], 
        line = dict( 
            width=20, 
            color='yellow' 
            ), 
        ), 
    secondary_y = False 
    ) 
fig.show() 

And immediately I got the idea... the only thing I needed to do was switch over the secondary_y axis. For some reason I can't figure out in the Plotly system, secondary_y axes items always overwrite the primary. Here's the final graph and the code.

All I had to do was flip the bar graph onto the first y-axis and the lines onto the secondary y-axis. I've done that now on my main graph and voila... it worked.

This isn't a finished product yet, it needs a fair bit of work, but here's the current draft.

You should be able to play with the interactive HTML version at this link.

Thanks for looking and I hope this helps someone one day!