OpenCV SVM error in calc_non_rbf_base()

#include <opencv2/core/core.hpp>
#include <opencv2/ml/ml.hpp>

using namespace cv;
using namespace std;

void main(){
    int number_samples = 10400;

    Mat labels(number_samples, 1, CV_32F, Scalar(0));

    int features_length = 206000;

    Mat descriptors(number_samples, features_length, CV_32F, Scalar(0));
    randn(descriptors, 0, 1);   //fill with random data

    SVM my_svm;
    SVMParams params;
    params.kernel_type = SVM::LINEAR;

    //This test case will succeed - clear imbalance of positive and negative samples
    labels.rowRange(0, number_samples / 40) = 1;

    try{
        cout << "Training SVM with feature length of: " << features_length << "...";
        my_svm.train(descriptors, labels, Mat(), Mat(), params);
        cout << "Done!" << endl;
    }
    catch (...){
        cout << "Exception ocurred while trying to train SVM" << endl;
    }

    //This test case will fail - same proportion of positive and negative samples
    labels.rowRange(0, number_samples / 2) = 1;

    try{
        cout << "Training SVM with feature length of: " << features_length << "...";
        my_svm.train(descriptors, labels, Mat(), Mat(), params);
        cout << "Done!" << endl;
    }
    catch (...){
        cout << "Exception ocurred while trying to train SVM" << endl;
    }

    //However, this test case will succeed again
    labels.rowRange(0, number_samples / 2) = 1;
    features_length = 205000;

    try{
        cout << "Training SVM with feature length of: " << features_length << "...";
        my_svm.train(descriptors, labels, Mat(), Mat(), params);
        cout << "Done!" << endl;
    }
    catch (...){
        cout << "Exception ocurred while trying to train SVM" << endl;
    }
}