Welcome @mr.berry 
Looks like the url routing didn’t get properly passed along to the front end - if you look at the network tab in developer tools, do you see a failed request for <host>/_dash-component-suites/dash_renderer/dash_renderer.dev.js?...? That probably needs to get myapp inserted after <host>, which is what requests_pathname_prefix is for:
app = dash.Dash(requests_pathname_prefix='/myapp/')