C++: IntelliSense fails for templates

Question

template <class T, class U> struct Additional {
    T t;
    U u;
};
template <class T, class U> struct Base {
    void test1() {
        additional-> // members are shown here
    }
    Additional<T, U>* additional;
};
template <class T, class U> struct Derived : Base<T, U> {
    void test2() {
        additional-> // IntelliSense: 'No members available'
    }
};

I marked with comments the points of interest. The goal is to access suggested members inside test2(). At the first time I tried to declare a template struct inside another template struct (Additional in Base), but the notation became complex so I switched to keep Additional outside. I'm making dynamic containers for kernel driver usage. VS2019, Win 10, latest updates for both. Some suggested variants that did not work:

template <class T, class U> struct Derived : Base<T, U> {
    void test2() {
        this->additional-> // This one passed the compile
    }
};
template <class T, class U> struct Derived : Base<T, U> {
    void test2() {
        Base<T, U>::
    }
};
template <class T, class U> struct Derived : Base<T, U> {
    using Base<T, U>::additional;
    void test2() {
        additional->
    }
};