Loading saved cv.DescriptorMatcher in MATLAB (mexopencv) - matlab

Question

I have recently started working in mexopencv and I am new to it. However, I have made a database of keypoints and features of images for ORB and SURF and saved it in a .mat file along with the trained matchers.
Matcher used:
FLANN based matcher (for SURF points)
BruteForce - Hamming (for ORB points)
It works fine if I train the data in the same script and try to find the image from the databse. However, when I try to find the image from the database in another script by loading the keypoints data and the matcher, it fails.
The code for making database is:
%% OPTIONS
SURF_Threshold = 40000;
%% SETUP
SURF = cv.SURF('HessianThreshold', SURF_Threshold);
ORB = cv.ORB;
opts = {'KDTree', 'Trees',5}; %Dictionary required for FLANN
matcherFLANN = cv.DescriptorMatcher('FlannBasedMatcher', 'Index',opts);
matcherBF = cv.DescriptorMatcher('BruteForce-Hamming');
foldername = uigetdir;
oldFolder = cd(foldername);
files = [dir('*.jpg');dir('*.png')]; %Look for jpg files in the directory.
N = size(files,1); %numel the files
%Create empty training sets
trainDataORB = struct('name', cell(N,1), 'pts',cell(N,1), 'feat',cell(N,1));
trainDataSURF = struct('name', cell(N,1), 'pts',cell(N,1), 'feat',cell(N,1));
%% TRAINING
for i=1:N
% read image
img = imread((files(i).name));
%Extracting keypoints and descriptors (features) for both
[trainDataSURF(i).pts, trainDataSURF(i).feat] = SURF.detectAndCompute(img);
[trainDataORB(i).pts, trainDataORB(i).feat] = SURF.detectAndCompute(img);
trainDataSURF(i).name = files(i).name;
trainDataORB(i).name = files(i).name;
% add to training set to match against for each of descriptor
matcherFLANN.add(trainDataSURF(i).feat);
matcherBF.add(trainDataORB(i).feat);
end
% build index
matcherFLANN.train();
matcherBF.train();
%% SAVING DATA
%Navigate back to old folder
cd(oldFolder);
save('training_data.mat', 'matcherFLANN', 'matcherBF', 'trainDataSURF','trainDataORB');
The matcher objects are then loaded with in another scrip (with cleared workspace):
load('training_data.mat');
Which returns the error:
Error using DescriptorMatcher_ Object not found id=109
Error in cv.DescriptorMatcher/match (line 461)
matches = DescriptorMatcher_(this.id, 'match', queryDescriptors, varargin{:});
Error in detection_Test (line 27)
matches = matcherFLANN.match(feat);
Any help would be gladly welcomed.