SetUserId does not work as expected

I am trying to track events from the .NET backend from the ASP.NET Core application. I can successfully track events in the Snowplow, but I am facing an issue while setting up an UserId while tracking an event.

I have followed this document but still, I am getting different values in the database “atomic”.events.user_id column.

Can someone please help me to figure that out?

Below is my code block,

            var subject = new Subject().SetUserId("userId-test-1");
            var sdEvent = GetSelfDescribingEventData();
            Tracker.Instance.Track(sdEvent, subject);

As per the code, I should get the userId-test-1 value in the “atomic”.events.user_id column but I am getting a different(random GUID).