[Fact]
public void Slow
{ 
    var fixture = new Fixture():

    var items1 = fixture.Create<List<Item>>();
    Nock.Arrange(() => ItemsRepository.GetItems1()).Returns(items1);

    var items2 = fixture.Create<List<Item>>();
    Nock.Arrange(() => ItemsRepository.GetItems2()).Returns(items2);

    var items3 = fixture.Create<List<Item>>();
    Nock.Arrange(() => ItemsRepository.GetItems3()).Returns(items3);

    var items4 = fixture.Create<List<Item>>();
    Nock.Arrange(() => ItemsRepository.GetItems4()).Returns(items4);
}

[Fact]
public void Fast()
{
    var fixture = new Fixture():

    var items1 = fixture.Create<List<Item>>();
    var items2 = fixture.Create<List<Item>>();
    var items3 = fixture.Create<List<Item>>();
    var items4 = fixture.Create<List<Item>>();

    Nock.Arrange(() => ItemsRepository.GetItems1()).Returns(items1);
    Nock.Arrange(() => ItemsRepository.GetItems2()).Returns(items2);
    Nock.Arrange(() => ItemsRepository.GetItems3()).Returns(items3);
    Nock.Arrange(() => ItemsRepository.GetItems4()).Returns(items4);
}

public interface IAnsweringService
{
    (int code, string desc) GetAnswer(string question);
}


[TestMethod]
public void AnswerToTheUniverseQuestionTest()
{
    var apiMock = Mock.Create<IAnsweringService>();

    var expectedAnswer = new { code = 42, desc = "Answer to the Ultimate Question of Life" };

    Mock.Arrange(() => apiMock.GetAnswer(Arg.AnyString)).Returns(expectedAnswer);

    var actualAnswer = apiMock.GetAnswer("What is a universe question answer?");

    Assert.AreEqual(expectedAnswer.code, actualAnswer.code);
    Assert.AreEqual(expectedAnswer.desc, actualAnswer.desc);
}

Telerik.JustMock.Core.MockException: The chained return value type '<>f__AnonymousType1`2[System.Int32,System.String]' is not compatible with the arranged method's return type 'System.ValueTuple`2[System.Int32,System.String]'

Mock.SetupStatic(typeof(TimeSpan), Behavior.CallOriginal, StaticConstructor.NonMocked);
Mock.Arrange(() => TimeSpan.FromSeconds(15)).Returns(TimeSpan.MinValue);

The issue can be temporary solved by disabling the DebugWindow via JustMock extension menu. 

public abstract class TestBase
{
    public static TestContext TestContext { get; set; }
}

[TestClass]
public class UnitTest1 : TestBase
{
    [ClassInitialize]
    public static void ClassInitlialize(TestContext ctx)
    {
        TestContext = ctx;
    }

    [TestMethod]
    public void TestMethod1()
    {

    }
}

[TestClass]
public class UnitTest2 : TestBase
{
    [ClassInitialize]
    public static void ClassInitlialize(TestContext ctx)
    {
        TestContext = ctx;
    }

    [TestMethod]
    public void TestMethod1()
    {

    }
}

Attempt to run the tests above with JustMock profiler enabled fails with System.InvalidProgramException. The issue is not reproducible with MSTest.TestFramework and MSTest.TestAdapter packages prior to 3.0.x.

[Theory]
[MemberData(nameof(GetMemberDataContext))]
public void ValidParameters_Success(int param1, int param2)
{
	// Arrange
	Mock.SetupStatic(typeof(MyClass), Behavior.Strict, StaticConstructor.Mocked);
        Mock.Arrange(() => MyClass.method1()).Returns(true);

        // Act
	IService service = new Service();
	bool result = service.method2();

	// Assert
	Assert.True(result);
	Mock.Assert(() => MyClass.method1(), Occurs.Once()); // <-- the test fails here because it reports that method invocation occurs twice
}

The issue in not observed if the code is modified in the following way, which indicates behavioral incinsistency:

[Theory]
[MemberData(nameof(GetMemberDataContext))]
public void ValidParameters_Success(int param1, int param2)
{
	// Arrange
	Mock.SetupStatic(typeof(MyClass), Behavior.Strict, StaticConstructor.Mocked);
        Mock.Arrange(() => MyClass.method1()).Returns(true).OccursOnce();

        // Act
	IService service = new Service();
	bool result = service.method2();

	// Assert
	Assert.True(result);
	Mock.Assert<MyClass>();
}

IEnumerable<IInvocaiton> invocations = foo.GetInvocationsFor((x) => x.CalcData(2, 2));