ASP.NET Web API work cors with identity server 4

Question

I try to connect the ASP.NET Web API (not .NET Core) with identity server.

I use owin as startup but I get a cors error.

Why does cors

app.UseCors(Microsoft.Owin.Cors.CorsOptions.AllowAll);

not work with UseOpenIdConnectAuthentication? It works when I remove it

public class Startup1
    {
 public void Configuration(IAppBuilder app)
        {
            app.UseCors(Microsoft.Owin.Cors.CorsOptions.AllowAll);
            app.UseOpenIdConnectAuthentication(new OpenIdConnectAuthenticationOptions
            {
                ClientId = "insig_spa",
                Authority = "https://localhost:5000",
                RedirectUri = "https://localhost:5002/auth-callback",
                Scope = "openid profile email insigapi.read",

                SignInAsAuthenticationType = "cookie",

                RequireHttpsMetadata = false,
                UseTokenLifetime = false,

                RedeemCode = true,
                SaveTokens = true,
                ClientSecret = "secret",

                ResponseType = OpenIdConnectResponseType.Code,
                ResponseMode = "query",

                Notifications = new OpenIdConnectAuthenticationNotifications
                {
                    RedirectToIdentityProvider = n =>
                    {
                        if (n.ProtocolMessage.RequestType == OpenIdConnectRequestType.Authentication)
                        {
                            // set PKCE parameters
                            var codeVerifier = CryptoRandom.CreateUniqueId(32);

                            string codeChallenge;
                            using (var sha256 = SHA256.Create())
                            {
                                var challengeBytes = sha256.ComputeHash(Encoding.UTF8.GetBytes(codeVerifier));
                                codeChallenge = Base64Url.Encode(challengeBytes);
                            }

                            n.ProtocolMessage.SetParameter("code_challenge", codeChallenge);
                            n.ProtocolMessage.SetParameter("code_challenge_method", "S256");

                            // remember code_verifier (adapted from OWIN nonce cookie)
                            RememberCodeVerifier(n, codeVerifier);
                        }

                        return Task.CompletedTask;
                    },
                    AuthorizationCodeReceived = n =>
                    {
                        // get code_verifier
                        var codeVerifier = RetrieveCodeVerifier(n);

                        // attach code_verifier
                        n.TokenEndpointRequest.SetParameter("code_verifier", codeVerifier);

                        return Task.CompletedTask;
                    }
                }
            });

        }
}