Version Used:

Microsoft Visual Studio Enterprise 2019 Preview
Version 16.0.0 Preview 1.1
VisualStudio.16.Preview/16.0.0-pre.1.1+28408.50
Microsoft .NET Framework
Version 4.7.03056

Steps to Reproduce:

Compile and run the following code

#nullable enable
class C
{
  C? f;
  static void Main()
  {
    new C() { f = { f = null }};
  }
}

https://sharplab.io/#v2:EYLgtghgzgLgpgJwDQxAgrgOyQExAagB8BiTdAG3ImHLgAI5NraBYAKAAEAmOgYXYDe7OnwD8dAGYBuYXQ4BGAGxyALHQCyEAJaYAFAEpZQtiJGY4Adz4G6AyXQC8t+07KU6AXw8yTn9h6A=

Expected Behavior:
Possible derefernce of a null reference warning for f = { f = null } initializer as it dereferences a field which is explicitly marked as nullable in order to set its properties.

Actual Behavior:
No warnings for nullable reference types. The program crashes at runtime with a NullReferenceException