IDE0059 - Unneccessary assignment is not reported if lambda is used in method

Version Used: VS16.3 Preview 2

Steps to Reproduce:

using System;

namespace TestNamespace
{
    public class TestClass
    {
        public void TestMethod()
        {
            var r = new Random();
            DoSmth(() => true);
        }

        private void DoSmth(Func<bool> func) => func();
    }
}

Expected Behavior: IDE0059 should be triggered for r.

Actual Behavior: IDE0059 is not triggered. If you comment out DoSmth(() => true);, IDE0059 is triggered as expected.