Blazor server logging in

I have a strange one with Blazor server. If i have configured as <component type=“typeof(App) render-mode=“ServerPrerendered” />” it works perfectly, it logs itself in automatically when a user details are there.

However, if i change to <component type=typeof(App)" render-mode=“Server” /> it does not log in, the user has to hit the login button. The url is https://localhost:7250/login?redirectUri=/, if I add a ? after the / it works but i can’t see how to configure that.

Any ideas please as to why it works when prerendering but doesn’t when not?