Update_yaxes(rangemode) is not taking effect, why?

I have the following code in my Dash Plotly app, but for some reason rangemode = ‘tozero’ does not take effect. I tried other properties in fig.update_yaxes and they all seem to take effect, problem is only with rangemode. Why would this happen ? I do not see any error messages when I run the code.

fig1.update_layout(yaxis={‘title’:‘MEASURED DATA’},
title={‘text’:‘Measured Data Plot’,
fig1.update_xaxes(type = ‘category’)
fig1.update_yaxes(rangemode = ‘tozero’)

By the way, this was working fine until a few minutes ago, wondering what could have happened since I did not change anything in the code.

Please include all relevant code, including dataframe. Also write the code in triple quotes so that other people could read and use it more easily. Are you using plotly.graph_objs or plotly.express?