Не работают перегруженные операторы в производном классе

#include <iostream>
using namespace std;
 
class PrefixCounter
{
protected:
    unsigned int count;
public:
    PrefixCounter() : count() {}
    PrefixCounter(int c) : count(c) {}
    unsigned int GetCount() const { return count; }
    PrefixCounter operator++() { return PrefixCounter(++count); }
    PrefixCounter operator--() { return PrefixCounter(--count); }
};
 
class PostfixCounter : public PrefixCounter
{
public:
    PostfixCounter() : PrefixCounter() {}
    PostfixCounter(int c) : PrefixCounter(c) {}
    PostfixCounter operator++(int) { return PostfixCounter(count++); }
    PostfixCounter operator--(int) { return PostfixCounter(count--); }
};
 
int main()
{
    setlocale(LC_ALL, "ru");
 
    PostfixCounter obj1 = 0;
    ++obj1;
    --obj1;
    cout << obj1.GetCount() << endl;
 
    return 0;
}

#include <iostream>
 
class PrefixCounter
{
protected:
    unsigned int count;
public:
    PrefixCounter() : count() {}
    PrefixCounter(int c) : count(c) {}
    unsigned int GetCount() const { return count; }
    PrefixCounter& operator++() { ++count; return *this;}
    PrefixCounter& operator--() { --count; return *this;}
};
 
class PostfixCounter : public PrefixCounter
{
public:
    using PrefixCounter::operator++;
    using PrefixCounter::operator--;
    PostfixCounter() : PrefixCounter() {}
    PostfixCounter(int c) : PrefixCounter(c) {}
    PostfixCounter operator++(int) { const auto copy=*this; ++count; return copy;}
    PostfixCounter operator--(int) { const auto copy=*this; --count; return copy;}
};
 
int main()
{
    setlocale(LC_ALL, "ru");
 
    PostfixCounter obj1 = 0;
    ++obj1;
    --obj1;
    obj1++;
    obj1--;
    std::cout << obj1.GetCount() << std::endl;
 
    return 0;
}

using PrefixCounter::operator++;
    using PrefixCounter::operator--;