Possible bug with static?

Here's the pseudo test code:

SupportingClass source = GenerateSourceWithValues("TEST");
Isolate.Fake.StaticMethods(typeof(Foo), Members.CallOriginal);

AnotherClass target = AnotherClass.FactoryMethod(source);

Assert.IsNotNull(target);
Isolate.Verify.WasCalledWithExactArguments(() => Foo.FactoryMethod(source.SomeProperty));

When executing (I'm still on 5.2.2 - can't go to 5.2.3 until later this week) I get the following exception from Isolator (not very clear by the way):

***Isolate.Verify does not support objects that were not fake using Isolate.Fake.Instance(), or passed through WhenCalled().

I tried several combinations, all of which resulted in the same error message:

SupportingClass source = GenerateSourceWithValues("TEST");
Isolate.WhenCalled(() => Foo.FactoryMethod(null)).CallOriginal();

AnotherClass target = AnotherClass.FactoryMethod(source);

Assert.IsNotNull(target);
Isolate.Verify.WasCalledWithExactArguments(() => Foo.FactoryMethod(source.SomeProperty));

and

SupportingClass source = GenerateSourceWithValues("TEST");
Isolate.Fake.StaticMethods(typeof(Foo));
Isolate.WhenCalled(() => Foo.FactoryMethod(null)).CallOriginal();

AnotherClass target = AnotherClass.FactoryMethod(source);

Assert.IsNotNull(target);
Isolate.Verify.WasCalledWithExactArguments(() => Foo.FactoryMethod(source.SomeProperty));

***Using 'WithAnyArguments' method results in the same problem.

More Info:::

So because I needed this test to run I switched syntax to following and it passes - now maybe this is all because Foo.FactoryMethod is internal and I'm using InternalsVisibleTo???? But it seems like my original test (at least one of them should work)

Tests that passes:

SupportingClass source = GenerateSourceWithValues("TEST");
Isolate.NonPulbic.WhenCalled(typeof(Foo), "FactoryMethod").CallOriginal();

AnotherClass target = AnotherClass.FactoryMethod(source);

Assert.IsNotNull(target);
Isolate.Verify.NonPublic.WasCalled(typeof(Foo), "FactoryMethod");