Multer.fields([...options]) only uploads file with first option

Question

I have nodejs app which uploads files to amazon s3, I am sending 2 separate type file values from frontend, one is single file and other is array of files so to handle this case i have this route setup

 app.post('/api/class/add',
    uploaders.multipleImageUpload.fields(
      [
        {
          name: 'icon', maxCount: 1
        },
        {
          name: 'galleryImages', maxCount: 15
        }
      ]
    ),
    ClassController.addClass);

my middleware function is this

const multipleImageUpload = multer({
  storage: multerS3({
    s3: s3,
    bucket: awsConfig.s3.bucketName,
    acl: 'public-read',
    key: function(req, file, cb) {
      cb(null,
        path.basename(
          file.originalname,
          path.extname(file.originalname)
        ) + '-' + Date.now() + path.extname(file.originalname));
    }
  }),
  limits: { fileSize: 10000000 }, // In bytes: 10000000 bytes = 10 MB
  fileFilter: function(req, file, cb){
    checkFileType(file, cb);
  }
});

function checkFileType(file, cb){
  // Allowed ext
  const filetypes = /jpeg|jpg|png|gif|bmp/;
  // Check ext
  const extname = filetypes.test(path.extname(file.originalname).toLowerCase());
  // Check mime
  const mimetype = filetypes.test(file.mimetype);
  if (mimetype && extname){
    return cb(null, true);
  } else {
    cb('Error: Images Only!');
  }
}

Now whenever i send request on above route only single file icon is uploaded to s3 bucket and then process moves to next function and there as well i see req.files array which only have one entry and that is icon file as well.

request data

name: abc
type: abc
description: abc
tags: abc,abc 2
classes: [object Object]
icon: (binary)
galleryImages: [object File],[object File],[object File],[object File],[object File]

and here is console.log(req.files)

[Object: null prototype] {
  icon: [
    {
      fieldname: 'icon',
      originalname: '1pcxst.jpg',
      encoding: '7bit',
      mimetype: 'image/jpeg',
      size: 83109,
      bucket: 'BUCKETNAME',
      key: '1pcxst-1592071524750.jpg',
      acl: 'public-read',
      contentType: 'application/octet-stream',
      contentDisposition: null,
      storageClass: 'STANDARD',
      serverSideEncryption: null,
      metadata: null,
      location: 'https://BUCKETNAME.s3.amazonaws.com/1pcxst-1592071524750.jpg',
      etag: '"f3ce110e00f7ebfe2f18c77f323fdd0b"',
      versionId: undefined
    }
  ]
}

I have checked checkFileType is called only once.