Error when loading torch model in OpenCV 3.4.1 Android

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I'm trying to do face recognition on Android using OpenFace nn4.small2.v1 neural network.

To see if the network could be loaded with OpenCV, I tried to run a code taken from GitHub that uses the model. Using the prebuilt Windows version of OpenCV, I can run the code and the network is loaded without a problem.
However, If I try to load the network on Android, readNetFromTorch fails with the error :

"The function/feature is not implemented (Unsupported Lua type) in void cv::dnn::experimental_dnn_v4::TorchImporter::readObject(), file /build/master_pack-android/opencv/modules/dnn/src/torch/torch_importer.cpp, line 981".

I am using Xamarin for my app, so I have a Xamarin.Android project, and a Android shared library project where I have my C++ code.

Here's the C# code that calls the native code :

[DllImport("OpenCV", EntryPoint = "TryOpenCV", CharSet = CharSet.Ansi)]
private static extern int TryOpenCV_native([MarshalAs(UnmanagedType.LPStr)]string netPath, [MarshalAs(UnmanagedType.LPStr)]string cascadePath);  

public static int TryOpenCV(string netPath, string cascadePath)
{
    return TryOpenCV_native(newPath, cascadePath);
}

And here's the C++ code :

extern "C" int TryOpenCV(const char *netPath, const char *cascadePath)
{
    if (netPath && cascadePath)
    {
        cv::Mat mat = cv::Mat(96, 96, CV_8UC1);
        cv::String m_sNetPath(netPath);
        cv::String m_sCascadePath(cascadePath);

        try 
        {
            bool testNetPath = cv::utils::fs::exists(m_sNetPath);
            bool testCascadePath = cv::utils::fs::exists(m_sCascadePath);

            cv::CascadeClassifier cascade;
            cascade.load(m_sCascadePath);
        if (cascade.empty()) 
        {
            cv::String empty("cascade is empty");
        }

            cv::dnn::Net torchNet = cv::dnn::readNetFromTorch(m_sNetPath);
            cv::Mat inputBlob = cv::dnn::blobFromImage(mat, 1. / 255, cv::Size(96, 96), cv::Scalar(), true, false);
            torchNet.setInput(inputBlob);
            torchNet.forward();

            mat.release();

            return 0;
        }
        catch (cv::Exception &e)
        {
            cv::String m_exception(e.what());
            return 1;
        }
    }

    return returnInt();
}

The filepath I have for netpath and cascadePath is something like "/data/user/0/com.my.app/files/name.of.file.xxx".
I can create a Mat, both testNetPath and testCascadePath are true and the cascade load successfully (at least I hope so, because it's not empty), so OpenCV is working, can see the files, and so should load them both.

Stepping through the C++ code also gives me error when calling e.what() for some reason, but I get the error string when debugging the C# side.
I really can't see what's wrong here, but I am new to C++ so maybe I'm missing something obvious.