Why does this work with MSVC but not with Mingw?

#define log(x) std::cout << x
using namespace std;

template<typename T> 
void print(optional<T> c) 
{ 
   log(c.value_or("Input was std::nullopt")); 
}

template<typename T1, typename... T2> 
void print(optional<T1> c, optional<T2...> cs) 
{ 
   log(c.value_or("Input was std::nullopt")); print(cs...); 
}

int main() {
    optional<string> val(nullopt);
    print(val);
    return 1;
}

On MSVC c++20 it works just fine but with g++ -std=c++2a it gives the following error:
error: expansion pattern 'cs' contains no argument packs
void print(optional c, optional<T2...> cs) { log(c.value_or("Input was std::nullopt")); print(cs...); }

The error only happens if i pass a nullopt value in. If i would pass a normal string to the variable it would also work fine.