I further investigated the issue and created an account for Logto cloud. When I use the Logto cloud everything works fine when I set a Resource.
Eventually it has something todo with Logto selfhosted running on http instead of https or there is a bug in the self hosted version?

@Json-exe yes, its' because of the https. Can you configure the local host for HTTPS?

I'll see if I can get a reverse proxy to run locally or how I can get logto to run under https on my machine.

I set up a Logto Instance on my server and put NGINX in front of it. I issued a certificate from Lets Encrypt and enabled https. But the issue with the Ressource still persists. Also in the example App I dont get Authenticated if I set a resource.

I now tried the following on my local machine:

• Create a self signed certificate and install it
• Using this tutorial to add the certificates as env variables to my local docker container to allow https
• Create a new App for the Blazor Server Example and a new API Resource
• Try to sign in

Once again I could not be authenticated although now even localhost had https (I also tried that on my server where nginx is then proxying to https://127.0.0.1:3002 and 3001 but that did not work either).

I have made some more tests. I have disabled Cloudflare to check if that was the problem and have created the same configuration I have used in Logto Cloud. My issue sadly still persists.
Here are some logs of the Authentication process in case you need it:
Blazor Logs:

info: Microsoft.AspNetCore.Authorization.DefaultAuthorizationService[2]
Authorization failed. These requirements were not met:
DenyAnonymousAuthorizationRequirement: Requires an authenticated user.
info: Microsoft.AspNetCore.Hosting.Diagnostics[1]
Request starting HTTP/2 GET https://localhost:44319/SignIn - - -
info: Microsoft.AspNetCore.Routing.EndpointMiddleware[0]
Executing endpoint 'HTTP: GET /SignIn'
info: Microsoft.AspNetCore.Authentication.OpenIdConnect.OpenIdConnectHandler[12]
AuthenticationScheme: Logto was challenged.
info: Microsoft.AspNetCore.Routing.EndpointMiddleware[1]
Executed endpoint 'HTTP: GET /SignIn'
info: Microsoft.AspNetCore.Hosting.Diagnostics[2]
Request finished HTTP/2 GET https://localhost:44319/SignIn - 302 - - 378.7587ms
info: Microsoft.AspNetCore.Hosting.Diagnostics[1]
Request starting HTTP/2 POST https://localhost:44319/Callback - application/x-www-form-urlencoded 502
info: Microsoft.AspNetCore.Authentication.Cookies.CookieAuthenticationHandler[10]
AuthenticationScheme: Logto.Cookie signed in.
info: Microsoft.AspNetCore.Hosting.Diagnostics[2]
Request finished HTTP/2 POST https://localhost:44319/Callback - 302 - - 255.4845ms
info: Microsoft.AspNetCore.Hosting.Diagnostics[1]
Request starting HTTP/2 GET https://localhost:44319/ - - -
info: Microsoft.AspNetCore.Routing.EndpointMiddleware[1]
Executed endpoint '/ (/)'
info: Microsoft.AspNetCore.Hosting.Diagnostics[2]
Request finished HTTP/2 GET https://localhost:44319/ - 200 - text/html;+charset=utf-8 311.7258ms
info: Microsoft.AspNetCore.Authentication.Cookies.CookieAuthenticationHandler[7]
Logto.Cookie was not authenticated. Failure message: No principal.
info: Microsoft.AspNetCore.Authorization.DefaultAuthorizationService[2]
Authorization failed. These requirements were not met:
DenyAnonymousAuthorizationRequirement: Requires an authenticated user.

My Logto Instance Logs:
Interaction started:

{
  "key": "Interaction.Create",
  "result": "Success",
  "ip": "---.---.--.--",
  "userAgent": "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/129.0.0.0 Safari/537.36",
  "userId": "g8jqzitis1fe",
  "applicationId": "rzoeztxfntj0f4us6szbz",
  "sessionId": "kkO1S80zXhouQyjgmkd4h",
  "params": {
    "nonce": "638635631980426641.Mzc4MjBiYjMtZjg3MC00NTE2LTlkNzgtOTQwZTY1NmI1ZThmZDUyZWRiYjEtMWM5Ni00MGVhLThjODctM2M2YjJlY2U1NGRj",
    "scope": "openid offline_access profile",
    "state": "CfDJ8PciJX1BI1tMhWzI08s0l5WsI65ESSIc9_96lYVmgnMetyCl5BGBWccyImGopc8RQOnXJOglvTc1KORX-beSvSCVYAYwrkdDuYoLKdfn1V1rFYb5uvm_k1RnlYHXpYHnFBZs5x0rFW6eY-MhXkI8HSPJyxApVx5aPEjuKotChY-3QkweO-q_cYpKFK37KtQDcWXwzwRxyit3LGmyKglYALRp_lTlBt5n7qGCzbzp-YT_cKJgf8QhQNif3clKW_12XBUvW4cp-TZvy98nnOfUlw0OYCyxaEpyzrAz8fLVIOq8M4NwRy_wa-JrOQBB18SykTgOUoHi1GYO_9yv4pmnAOWDqtLdS0CLutQLajtDr229CLy-48MtQn9ROO7N6z_SsQ",
    "prompt": "consent",
    "resource": "http://localhost:3212/",
    "client_id": "rzoeztxfntj0f4us6szbz",
    "redirect_uri": "https://localhost:44319/Callback",
    "response_mode": "form_post",
    "response_type": "code",
    "code_challenge": "aUW0QhTkN3dSfi0H1Y1OBo-ZBLcQH29rkKiXZLj_Oc8",
    "code_challenge_method": "S256"
  },
  "prompt": {
    "name": "consent",
    "details": {
      "missingOIDCScope": [
        "openid",
        "offline_access",
        "profile"
      ]
    },
    "reasons": [
      "consent_prompt",
      "op_scopes_missing"
    ]
  },
  "interactionId": "aM-nCV2qU0qYnImOhASAB"
}

Exchange:

{
  "key": "ExchangeTokenBy.AuthorizationCode",
  "result": "Success",
  "ip": "---.---.--.--",
  "userAgent": "Microsoft ASP.NET Core OpenIdConnect handler",
  "userId": "g8jqzitis1fe",
  "applicationId": "rzoeztxfntj0f4us6szbz",
  "params": {
    "code": "IFjuozuL37jbMMwT3bu50poMpAGgOpmNa94sxu1zdZo",
    "client_id": "rzoeztxfntj0f4us6szbz",
    "grant_type": "authorization_code",
    "redirect_uri": "https://localhost:44319/Callback",
    "client_secret": "#internal:83N3UwftTlIRqeXKSgMiVFz98Bv1fv8B",
    "code_verifier": "OX4EDW35U5l9wCPY_8Gxzvo004SFjfNzYA6s335UKsE"
  },
  "scope": "openid offline_access profile",
  "tokenTypes": [
    "AccessToken",
    "RefreshToken",
    "IdToken"
  ],
  "applicationSecret": {
    "name": "Default secret"
  }
}

And my browser network logs:
localhost.json

Hope that helps.