rectpack2D: Regression in results from old rectpack2D

Hi, I am comparing the results of the old and current rectpack2D version. It appears the old version performs better in terms of the packing.

Results from the old version (33 rectangles packed):

Results from the current version (find_best_packing(), 12 rectangles packed):

Results from the current version (find_best_packing_dont_sort(), 22 rectangles packed):

This is the code I use in the new version:

    using spaces_type = rectpack2D::empty_spaces<true, rectpack2D::default_empty_spaces>;
    using rect_type = spaces_type::output_rect_type;
    std::vector<rect_type> rectangles;
    std::vector<bool> acceptedRects;
    int numAcceptedRects = 0;
    for (auto& img : sourceImages) {
      rectangles.emplace_back(rectpack2D::rect_xywh(0, 0, ofx::width(img->bounds()) + xMargin, ofx::height(img->bounds()) + yMargin));
      acceptedRects.push_back(false);
    }
    int maxSize = std::max(width, height) - std::max(xMargin, yMargin);
    auto reportUnsuccessful = [&](rect_type& rect) { return false; };
    auto reportSuccessful = [&](rect_type& rect) {
      int index = (&rect - rectangles.data());
      acceptedRects[index] = true;
      numAcceptedRects++;
      return !effect.abort();
    };
    std::cout << "sourceImages.size(): " << sourceImages.size() << "\n";
    std::cout << "rectangles.size(): " << rectangles.size() << "\n";
    std::cout << "discardStep: " << discardStep << "\n";
    std::cout << "maxSize: " << maxSize << "\n";
    rectpack2D::rect_wh const resultSize = rectpack2D::find_best_packing<spaces_type>(
      rectangles,
      rectpack2D::make_finder_input(
        maxSize,
        discardStep,
        reportSuccessful,
        reportUnsuccessful
      )
    );

Any idea where that regression comes from? Is it due to how I use the new version?