Inherited virtual properties are broken in Isolator 5.4.5

Here's the code that worked fine for months. It was broken by newest Isolator version (5.4.5):

    public class BaseClass
    {
        protected bool m_Enabled;

        public virtual bool Enabled1 { get { return m_Enabled; } set { m_Enabled = value; } }
        public virtual bool Enabled2 { get; set; }
        public virtual bool GetEnabled() { return false; }
    }

    public class SubClass : BaseClass
    {
    }

    [TestFixture]
    [Isolated]
    public class TestClass2
    {
        [Test]
        public void Enabled1_BaseClass()
        {
            var fake = Isolate.Fake.Instance<BaseClass>();
            Isolate.Swap.NextInstance<BaseClass>().With(fake);

            BaseClass bc = new BaseClass();
            bc.Enabled1 = false;
            Assert.IsFalse(bc.Enabled1);
        }

        [Test]
        public void Enabled1_SubClass()
        {
            var fake = Isolate.Fake.Instance<SubClass>();
            Isolate.Swap.NextInstance<SubClass>().With(fake);

            SubClass sc = new SubClass();
            sc.Enabled1 = false;
            Assert.IsFalse(sc.Enabled1);
        }

        [Test]
        public void Enabled2_BaseClass()
        {
            var fake = Isolate.Fake.Instance<BaseClass>();
            Isolate.Swap.NextInstance<BaseClass>().With(fake);

            BaseClass bc = new BaseClass();
            bc.Enabled2 = false;
            Assert.IsFalse(bc.Enabled2);
        }

        [Test]
        public void Enabled2_SubClass()
        {
            var fake = Isolate.Fake.Instance<SubClass>();
            Isolate.Swap.NextInstance<SubClass>().With(fake);

            SubClass sc = new SubClass();
            sc.Enabled2 = false;
            Assert.IsFalse(sc.Enabled2);
        }

        [Test]
        public void GetEnabled_BaseClass()
        {
            var fake = Isolate.Fake.Instance<BaseClass>();
            Isolate.Swap.NextInstance<BaseClass>().With(fake);

            BaseClass bc = new BaseClass();
            Assert.IsFalse(bc.GetEnabled());
        }

        [Test]
        public void GetEnabled_SubClass()
        {
            var fake = Isolate.Fake.Instance<SubClass>();
            Isolate.Swap.NextInstance<SubClass>().With(fake);

            SubClass sc = new SubClass();
            Assert.IsFalse(sc.GetEnabled());
        }
    }

All tests should pass. However, two of them fail with "null reference" exception:

TestCase 'TypeMockTest.TestClass2.Enabled1_SubClass'
failed: System.NullReferenceException : Object reference not set to an instance of an object.
at e1.a(MethodBase A_0, Object[] A_1)
at f8.a(MethodBase A_0, Object[] A_1, TypeParams A_2)
at ce.a(String A_0, Object[] A_1, Object A_2, Object A_3, String A_4, Type A_5)
at c8.a(String A_0, Object A_1, MethodBase A_2, Object[] A_3, Object A_4, String A_5, ce A_6)
at c8.b(Object A_0, String A_1, String A_2, MethodBase A_3, Object[] A_4, Object A_5)
C:ProjectsNETTypeMockTestMyClass2.cs(15,0): at TypeMockTest.BaseClass.set_Enabled1(Boolean value)
C:ProjectsNETTypeMockTestMyClass2.cs(46,0): at TypeMockTest.TestClass2.Enabled1_SubClass()
at TypeMock.MockManager.a(String A_0, String A_1, Object A_2, Object A_3, Boolean A_4, Object[] A_5)
at TypeMock.InternalMockManager.getReturn(Object that, String typeName, String methodName, Object methodParameters, Boolean isInjected)
C:ProjectsNETTypeMockTestMyClass2.cs(41,0): at TypeMockTest.TestClass2.Enabled1_SubClass()

TestCase 'TypeMockTest.TestClass2.Enabled2_SubClass'
failed: System.NullReferenceException : Object reference not set to an instance of an object.
at e1.a(MethodBase A_0, Object[] A_1)
at f8.a(MethodBase A_0, Object[] A_1, TypeParams A_2)
at ce.a(String A_0, Object[] A_1, Object A_2, Object A_3, String A_4, Type A_5)
at c8.a(String A_0, Object A_1, MethodBase A_2, Object[] A_3, Object A_4, String A_5, ce A_6)
at c8.b(Object A_0, String A_1, String A_2, MethodBase A_3, Object[] A_4, Object A_5)
at TypeMockTest.BaseClass.set_Enabled2(Boolean value)
C:ProjectsNETTypeMockTestMyClass2.cs(68,0): at TypeMockTest.TestClass2.Enabled2_SubClass()
at TypeMock.MockManager.a(String A_0, String A_1, Object A_2, Object A_3, Boolean A_4, Object[] A_5)
at TypeMock.InternalMockManager.getReturn(Object that, String typeName, String methodName, Object methodParameters, Boolean isInjected)
C:ProjectsNETTypeMockTestMyClass2.cs(63,0): at TypeMockTest.TestClass2.Enabled2_SubClass()


4 passed, 2 failed, 0 skipped, took 1,42 seconds (NUnit 2.5).