Hover show two y values at the pos x in one curve relation

Hi all,

I have a graph with some line curves and one curve with min and max values wich is shown as a filled area with following Python3 code:

y_upper = self.m_data[columnY]
y_lower = self.m_data[columnY2]

graph.add_trace(go.Scatter(
x=np.concatenate([times, times[::-1]]),
y=pd.concat([y_upper, y_lower[::-1]]),
fill=‘toself’,
fillcolor=fillcolor,
line_color=linecolor,
visible=True,
hoveron=‘points’,
name=“MinMax”
),subplot+1,1,secondary_y=secondaryyaxis)

This is working quiet good.

Problem:
My hovermode is “x unified” and in the hover only the upper value is shown:

Question:
How is it possible to show there both, lower and upper value? In the screenshot should be visible 900 and 100 at Min/Max Lin2…

Edit:

I discovered the customdata and changed my code to:

y_upper = self.m_data[columnY]
y_lower = self.m_data[columnY2]
customdata = [y_upper,y_lower]
// I also tried:
// customdata = [pd.concat([y_upper, y_upper[::-1]]),pd.concat([y_lower, y_lower[::-1]])]

graph.add_trace(go.Scatter(
x=np.concatenate([times, times[::-1]]),
y=pd.concat([y_upper, y_lower[::-1]]),
fill=‘toself’,
fillcolor=fillcolor,
line_color=linecolor,
visible=True,
hoveron=‘points’,
name=“MinMax”,
customdata = customdata,
hovertemplate="%{customdata[0]} - %{customdata[1]}"
),subplot+1,1,secondary_y=secondaryyaxis)

But result was:

Whats wrong with the template? Or what’s wrong with my customdata?

Thx and best regards
Klaus