ActivityResultHandler sometimes not working

Question

Im using a slightly modified version of the Gluon AndroidPicturesService (to be able to access the taken / selected picture). While taking or selecting a picture is basically working, sometimes there is no activity result and the app gets new initialized, i.e. there is no FXActivity onRestart prior to onStart, onResume, or even worse there is a crash (it seems not to be caused by a specific image or directory).

public class AndroidPictureService {

    private static final int      TAKE_PICTURE   = 1;
    private static final int      SELECT_PICTURE = 2;

    private File                  imageFile;
    private ObjectProperty<Image> image;

    public AndroidPictureService() {
    }

    public ObjectProperty<Image> imageProperty() {
        if (image == null) {
            image = new SimpleObjectProperty<>();
        }
        return image;
    }


    public void takePicture(int width, int height, boolean savePicture) {
        Intent intent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);

        File sourceFile = createImageFile();
        Uri imageUri = Uri.fromFile(sourceFile);

        intent.putExtra(MediaStore.EXTRA_OUTPUT, imageUri);

        FXActivity.getInstance().setOnActivityResultHandler((requestCode, resultCode, data) ->
        {
            if (requestCode == TAKE_PICTURE) {
                if (resultCode == RESULT_OK) {
                    MediaScannerConnection.scanFile(FXActivity.getInstance(), new String[] { sourceFile.toString() }, null, null);

                    if (width > 0 && height > 0) {
                        File tmpFile = new File(FXActivity.getInstance().getFilesDir(), "image_tmp.jpg");
                        adjustSizeAndStoreImage(sourceFile, tmpFile, width, height);
                        imageFile = tmpFile;
                    } else {
                        imageFile = sourceFile;
                    }

                    image.set(new Image(Uri.fromFile(imageFile).toString()));

                    if (!savePicture) {
                        sourceFile.delete();
                    }
                }
                Platform.runLater(() ->
                {
                    try {
                        Toolkit.getToolkit().exitNestedEventLoop(imageProperty(), null);
                    } catch (Exception e) {
                        System.out.println("GalleryActivity: exitNestedEventLoop failed: " + e);
                    }
                });
            }
        });

        if (intent.resolveActivity(FXActivity.getInstance().getPackageManager()) != null) {
            FXActivity.getInstance().startActivityForResult(intent, TAKE_PICTURE);
            try {
                Toolkit.getToolkit().enterNestedEventLoop(imageProperty());
            } catch (Exception e) {
                System.out.println("GalleryActivity: enterNestedEventLoop failed: " + e);
            }
        } else {
            System.out.println("GalleryActivity: resolveActivity failed");
        }
    }

    public void retrievePicture(int width, int height) {
        Intent intent = new Intent(Intent.ACTION_GET_CONTENT);
        intent.setType("image/*");

        FXActivity.getInstance().setOnActivityResultHandler((requestCode, resultCode, data) ->
        {
            if (requestCode == SELECT_PICTURE && resultCode == RESULT_OK) {
                Uri selectedImageUri = data.getData();

                String selectedImagePath = FileUtils.getPath(FXActivity.getInstance(), selectedImageUri);
                if (selectedImagePath != null && !selectedImagePath.isEmpty()) {
                    File sourceFile = new File(selectedImagePath);

                    if (width > 0 && height > 0) {
                        File tmpFile = new File(FXActivity.getInstance().getFilesDir(), "image_tmp.jpg");
                        adjustSizeAndStoreImage(sourceFile, tmpFile, width, height);
                        imageFile = tmpFile;
                    } else {
                        imageFile = sourceFile;
                    }

                    imageProperty().set(new Image(Uri.fromFile(imageFile).toString()));
                }

                Platform.runLater(() ->
                {
                    try {
                        Toolkit.getToolkit().exitNestedEventLoop(imageProperty(), null);
                    } catch (Exception e) {
                        System.out.println("GalleryActivity: exitNestedEventLoop failed: " + e);
                    }
                });
            }
        });

        // check for permissions
        if (intent.resolveActivity(FXActivity.getInstance().getPackageManager()) != null) {
            FXActivity.getInstance().startActivityForResult(Intent.createChooser(intent, "Select Picture"), SELECT_PICTURE);
            try {
                Toolkit.getToolkit().enterNestedEventLoop(imageProperty());
            } catch (Exception e) {
                System.out.println("GalleryActivity: enterNestedEventLoop failed: " + e);
            }
        } else {
            System.out.println("GalleryActivity: resolveActivity failed");
        }
    }

@Override
public void adjustSizeAndStoreImage(File sourceFile, File targetFile, int width, int height) {
    try (InputStream inForSizeCalculation = new FileInputStream(sourceFile);
            InputStream inForBitmapCreation = new FileInputStream(sourceFile);
            OutputStream out = new FileOutputStream(targetFile);) {

        BitmapFactory.Options options = new BitmapFactory.Options();
        options.inJustDecodeBounds = true;

        BitmapFactory.decodeStream(inForSizeCalculation, null, options);

        int scale = calculateInSampleSize(options, width, height);

        options.inJustDecodeBounds = false;
        options.inSampleSize = scale;

        Bitmap bitmap = BitmapFactory.decodeStream(inForBitmapCreation, null, options);

        bitmap.compress(CompressFormat.JPEG, 100, out);

    } catch (IOException ex) {
        LOGGER.error("Failed to adjustSizeAndStoreImage", ex);
    }
}  

    private int calculateInSampleSize(BitmapFactory.Options options, int reqWidth, int reqHeight) {
        final int height = options.outHeight;
        final int width = options.outWidth;
        int inSampleSize = 1;

        if (height > reqHeight || width > reqWidth) {
            final int halfHeight = height / 2;
            final int halfWidth = width / 2;

            while (halfHeight / inSampleSize >= reqHeight && halfWidth / inSampleSize >= reqWidth) {
                inSampleSize *= 2;
            }
        }
        return inSampleSize;
    }

    private File createImageFile() {
        String timeStamp = DateTimeFormatters.createTimeStamp();
        String imageFileName = "IMG_" + timeStamp + ".jpg";

        File storageDir = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES);
        return new File(storageDir, imageFileName);
    }

}