OpenCv SimpleBlobDetector does not find all blobs. C++ , VS2015

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I have a simple task for OpenCV SimpleBlobDetector

cv::SimpleBlobDetector::Params params;
cv::Ptr<cv::SimpleBlobDetector> detector = cv::SimpleBlobDetector::create(params);
std::vector<cv::KeyPoint> keypoints;
detector->detect(crop, keypoints);
drawKeypoints(crop, keypoints, crop, cv::Scalar(0, 0, 255), cv::DrawMatchesFlags::DRAW_RICH_KEYPOINTS);
cv::imshow("crop", crop);
cv::waitKey(0);

It is not detecting half of the blobs in my image. Please see picture below,

I tried adding parameters and varying them, at no point has it ever detected every single blob. Blob detection is a simple and straightforward algorithm that should be completely refined in every image processing API. Is this not the case with OpenCV?

All of these parameters were commented out when the image was taken, only the code above was executed

//params.minThreshold = 0;
//params.maxThreshold = 255;
//params.filterByArea = true;
//params.minArea = 1000;
//params.maxArea = 5000;
//params.filterByCircularity = true;
//params.minCircularity = 0.4;
//params.filterByConvexity = true;
//params.minConvexity = 0.87;
//params.filterByInertia = true;
//params.minInertiaRatio = 0.71;

I'm using either OpenCV 3.3 or 3.2, I can't seem to find the version number in the sources