Configuring an SSO flow with SPA and Logical API not working

Hi! I have a question about the SSO login flow for an SPA.

For our project, we have one application of type Single Page Application. This application is used by multiple frontends with different URLs, but the same top domain (e.g.,, etc). We used to service the backends for each of these frontends with separate APIs in Auth0, each with their own unique audience.

With the above setup, when the end user switches between our frontends, they have to login again. We want to enable SSO for our users so that this is no longer necessary. For this, we followed this Auth0 guide to setup a single Auth0 API that services all our frontends and accompanying backends.

When testing this locally, while running our frontends/backends on different localhost ports, this approach worked! We could sign in to one application, and when moving to another, we were automatically authenticated. However, after pushing this to our dev environment, the SSO didn’t work like on our local machine. Logging in worked just as before.

For both our local development and our dev environment, we use the same Auth0 application and Auth0 API. The only meaningful things that have changed (as far as I can tell) are the URLs we point to. Both the dev URLs and localhost URLs/ports are configured in our Auth0 application.

Does anyone know what might be causing this problem?