What's the best way to ensure a base class's static constructor is called?

You may call static constructor explicity, so you will not have to create any methods for initialization:

System.Runtime.CompilerServices.RuntimeHelpers.RunClassConstructor(typeof (TypeBase).TypeHandle);

You may call it in static constructor of derived class.

As others have noted, your analysis is correct. The spec is implemented quite literally here; since no member of the base class has been invoked and no instance has been created, the static constructor of the base class is not called. I can see how that might be surprising, but it is a strict and correct implementation of the spec.

I don't have any advice for you other than "if it hurts when you do that, don't do that." I just wanted to point out that the opposite case can also bite you:

class Program 
{
  static void Main(string[] args)
  {      
    D.M();
  }      

}
class B 
{ 
  static B() { Console.WriteLine("B"); }
  public static void M() {}
} 
class D: B 
{ 
  static D() { Console.WriteLine("D"); }
}

This prints "B" despite the fact that "a member of D" has been invoked. M is a member of D solely by inheritance; the CLR has no way of distinguishing whether B.M was invoked "through D" or "through B".

The rules here are very complex, and between CLR 2.0 and CLR 4.0 they actually changed in subtle and interesting ways, that IMO make most "clever" approaches brittle between CLR versions. An Initialize() method also might not do the job in CLR 4.0 if it doesn't touch the fields.

I would look for an alternative design, or perhaps use regular lazy initialization in your type (i.e. check a bit or a reference (against null) to see if it has been done).