FindAsync is not working properly about mockqueryable HOT 7 CLOSED

private Mock<IOrderManagerUnitOfWork<OrderManagerContext>> _uow = new Mock<IOrderManagerUnitOfWork<OrderManagerContext>>();
 var countries = CountryStub.GetCountries().AsQueryable().BuildMockDbSet(); // GetCountries()r returns List<Country>
            countries.Setup(x=>x.FindAsync(1)).ReturnsAsync((object[] ids) =>
            {
                return countries.Object.FirstOrDefault(x => x.Id == 1);
            }); //also why I should do this, Im basically mocking the data (DbSet), so I expect the linq extension methods will work on mocked collection
            _uow.Setup(x => x.Context.Set<Country>()).Returns(countries.Object);
            var repository = new CountryRepository(_uow.Object); //passing context containing mocked DbSet wrapped in UOW
            var result = await repository.FindByIdAsync(1); //internally calls FindAsync(id)
            Assert.IsNotNull(result); //still null

internal class MyTestClass: IOrderManagerUnitOfWork<OrderManagerContext>{
    DbSet<Country> _countryDbset;
   public MyTestClass(DbSet<Country> countryDbset){
           _countryDbset = countryDbset;
    }
   ...
    public Set<Country>
   {
         get{
               return _countryDbset;
          }
   }
   ...
} 

 countries.Setup(x => x.FindAsync(It.IsAny<object[]>())).ReturnsAsync((object[] ids) =>
            {
                return CountryStub.GetCountries().FirstOrDefault(x => x.Id == 1);
            }); 

object[] args = new object[1];
args[0] = 1;
 countries.Setup(x => x.FindAsync(args)).ReturnsAsync((object[] ids) =>
            {
                return CountryStub.GetCountries().FirstOrDefault(x => x.Id == 1);
            });

  var mock = users.AsQueryable().BuildMockDbSet();
      mock.Setup(x => x.FindAsync(It.IsAny<object[]>())).ReturnsAsync((object[] ids) =>
      {
        var id = (Guid) ids.First();
        return users.FirstOrDefault(x => x.Id == id);
      });