dcc.Store data prop is getting set to null on tab change

I’m only having this issue when I deploy to heroku. It doesn’t occur when I run locally. I checked in the react dev tools and noticed that the data prop is getting set to null for some reason. Any idea why this is occuring?

Here is the only callback that is updating my store component:

@app.callback(Output('country-cache', 'data'),
              [Input('total-emp-tab-dropdown', 'value'),
               Input('temp-emp-tab-dropdown', 'value')],
               [State('tabs', 'value')])
def store_country_cache(total_emp_country, temp_emp_country, tab):
    if tab == 'total-emp':
        return total_emp_country
    elif tab == 'temp-emp':
        return temp_emp_country

And here is a gif illustrating this: