Unity compiler is buggy

gistfile1.txt

        ctx => { var i = ctx._1; var bi = ctx._2; var map = ctx._3;
          Log.editor("flatMap subIter skip: \n  ctx=" + ctx + "\n  i=" + i + "\n  bi=" + bi);
          
Outputs:
  
  ctx=(
    Iter(Some((System.Collections.Generic.List`1[System.Int32],0,False))|sh:Some(3)),
    Iter(Some((System.Collections.Generic.List`1[System.Int32],0,False))|sh:Some(2)),
    System.Fn`2[System.Int32,com.tinylabproductions.TLPLib.Iter.Iter`2[System.Int32,System.Tpl`3[System.Collections.Generic.IList`1[System.Int32],System.Int32,System.Boolean]]]
  )
  i=Iter(Some((System.Collections.Generic.List`1[System.Int32],0,False))|sh:Some(3))
  bi=Iter(Some((System.Collections.Generic.List`1[System.Int32],0,False))|sh:Some(3))
  
If ctx = struct Tpl<P1, P2, P3> {
  public readonly P1 _p1;
  public readonly P2 _p2;
  public readonly P3 _p3;
}

Works with ctx = struct Tpl<P1, P2, P3> {
  public P1 _p1 { get; private set; }
  public P2 _p2 { get; private set; }
  public P3 _p3 { get; private set; }
}