FakeItEasy - Faked method calls within tasks don't work all of the time

MyTestClass.cs

using System.Threading;
using System.Threading.Tasks;

using FakeItEasy;

using Microsoft.VisualStudio.TestTools.UnitTesting;

public interface ITestInterface
{
    int MyMethod();
}

[TestClass]
public class UnitTest1
{
    [TestMethod]
    public void TestMethod1()
    {
        ITestInterface fake = A.Fake<ITestInterface>();

        int count = 0;
        A.CallTo(() => fake.MyMethod()).ReturnsLazily(p => Interlocked.Increment(ref count));

        Task<int>[] tasks =
        {
            Task.Run(() => fake.MyMethod()),
            Task.Run(() => fake.MyMethod()),
        };

        int[] result = Task.WhenAll(tasks).Result;

        CollectionAssert.AreEquivalent(new[] {1, 2}, result);

        // Assertion fails NEVER with FakeItEasy 2.3.1
        // Assertion fails sometimes with FakeItEasy 4.7.1
        // Assertion fails sometimes with FakeItEasy 4.9.0
        // Message: "Expected to find it twice exactly but found it once among the calls: ..."
        A.CallTo(() => fake.MyMethod()).MustHaveHappened(Repeated.Exactly.Twice);
    }
}