Debugging issue Visual Studio Code

I have some issue with debugging in VS Code on Mac:

'Step into' breaks debugging at the line where there are properties or methods of Unity classes. For example, can't debug code like this:

 // Use this for initialization
 void Start ()
 {
     Func(transform.right.x);
 
 }
 void Func(float x)
 {
     Debug.Log(x);
 }
 

All debug options (Step Over, Step Into) become greyed when I click 'Step Into' at line with Func reference (line 4). But the same code can be perfectly debugged when I first cache function argument.

 // Use this for initialization
 void Start ()
 {
     float transformX = transform.right.x;
     Func(transformX);
 
 }
 void Func(float x)
 {
     Debug.Log(x);
 }

Nevertheless, if I click occasionally 'Step Into' at line 4 in new code, then debugging stops. Is it a bug or am I missing something?