I've created two classes, with one of them having an implicit cast between them:

public class Class1
{
    public int Test1;
}

public class Class2
{
    public int Test2;

    public static implicit operator Class1(Class2 item)
    {
        return new Class1{Test1 = item.Test2};
    }
}

When I create a new list of one type and try to Cast<T> to the other, it fails with an InvalidCastException:

List<Class2> items = new List<Class2>{new Class2{Test2 = 9}};
foreach (Class1 item in items.Cast<Class1>())
{
    Console.WriteLine(item.Test1);
}

This, however, works fine:

foreach (Class1 item in items)
{
    Console.WriteLine(item.Test1);
}

Why is the implicit cast not called when using Cast<T>?