Silent authentication using a proxy

We are using Auth0 behind a gateway proxy. So the client will be interacting with this proxy for authorize , token, userinfo etc endpoint calls.
We are authenticating users from SPA with Auth code + PKCE method ( so the user will be redirected to Auth0 login page for authentication ). Proxy will take care of redirect response from Auth0 and final response is sent back to the client from proxy.
Everything is fine and working as expected until we met with the silent authentication.
For the silent auth request, gateway proxy will redirect the request to Auth0 and we are getting a proper response from Auth0 as well. But the auth0 js sdk is not processing the response. After 60 seconds I am getting a timeout error in the console.
When I checked, I could see that the silent auth request is triggered from an iframe ? Can I get your expert suggestion on why the iframe may not be responding to the success response from Auth0?