Dash app works in gunicorn, it doesn't behind nginx

I’ve created an app based on flask+dash. it works on spyder, it works on gunicorn, it does not as i put gunicorn behind nginx.
Follows the python code

appReporting = dash.Dash(
server=app, url_base_pathname=’/reporting/’, meta_tags=[{“name”: “viewport”, “content”: “width=device-width”}]
appReporting.layout = html.Div(
[dcc.Location(id=“url”, refresh=False),

@appReporting.callback(Output(“page-content”, “children”), [Input(“url”, “pathname”)])
def display_page(pathname):
ctx = dash.callback_context
for i in ctx.inputs_list:
if (pathname == ‘XXXX’): return blabla
else return bloblo

After some investigation, when using nginx, the callback is invoked but pathname is set to None.
I tried also to replace url with href to get the full url and it yet does not work, href is set to None.

More in detail, as I set a default page in the callback, nginx displays the default page all the times.

Have you any suggestion what to check in nginx configuration to sort this out?