localhost cookies not set

I highly suspect that localhost is not a valid domain name so Chrome rejects it. If you simply remove 'domain=localhost' from the Set-Cookie then it will work and Chrome will assign the domain to localhost for you.

I would personally create a local domain name like "test.dev" and add it to your Windows hosts file, 127.0.0.1 test.dev

I ran into this issue today and Gaui's answer was quite useful to me, bearing in mind ideally you do not want to open up your server to CORS requests from any site. I'm in my dev environment and my server and client are on different origins since they are on different ports on localhost. Also I'm using .net core 3.0

My issue was caused by my server not sending cookies to my client side as my CORS settings were blocking the sending of cookie to my domain this was evident by the server not using the header Access-Control-Allow-Credentials: true. To resolve this I configured my server in Startup.cs to allow requests from my client side to allow credentials (A credential is a cookie's authorization headers or TLS client certificates).

        var allowedOrigins = new[] {"localhost:3000"}; // Ideally comes from appsettings

        app.UseCors(builder =>
            builder.WithOrigins(allowedOrigins).AllowCredentials().AllowAnyMethod().AllowAnyHeader().Build());

For the cookie options; I found that the you do not have to set Domain if you do not want to, Secure works even when the site is not using https.

Google chrome now supports cookies on localhost, I believe it didn't used to as a lot of older SO posts have users who faced that issue.

On the client side, you need to configure it to accept cookies as well, as in Gaui's answer above. I was using fetch, and so had to add the option:

credentials: 'include'

Which tells fetch to retrieve cookies across domains. See the docs here