Problem with implementation

The following very simple program runs with Conda (no error message, but does not show any plot but black window. Any help is greatly appreciated. (I of course imported plotly) I use Spyder.

import plotly.express as px
data=[[1, 25, 30, 50, 1], [20, 1, 60, 80, 30], [30, 60, 1, 5, 20]]
fig = px.imshow(data,
labels=dict(x=“Day of Week”, y=“Time of Day”, color=“Productivity”),
x=[‘Monday’, ‘Tuesday’, ‘Wednesday’, ‘Thursday’, ‘Friday’],
y=[‘Morning’, ‘Afternoon’, ‘Evening’]
)
fig.update_xaxes(side=“top”)
fig.show()

Thanks

Elia