Version Used: Version 16.4.0 Preview 2.0 [29315.5.master]

Steps to Reproduce:

class F
{
    public override string ToString() // caret on ToString here
    {
        return base.ToString();
    }
}

With the caret on ToString in the method signature, invoke "Go to base".

Expected Behavior:

Does the same as "Go to definition" on base.ToString() call (i.e. MAS).

Actual Behavior:

Dialog appears saying:

The symbol has no base.