Express-Fileupload not parsing files in heroku

Question

I am using express-fileupload to parse the body of my request and access any files that are sent with the request. This works fine when I am trying to do this locally but when I push it to heroku, the files are not being parsed - instead req.files is null. My code is below:

Parsing middleware:

var cookieParser = require('cookie-parser');
var bodyParser = require('body-parser');
const fileUpload = require('express-fileupload');

module.exports = function (app) {
    app.use(cookieParser());
    app.use(bodyParser.json());
    app.use(bodyParser.urlencoded({ extended: true }));
    app.use(fileUpload());  // EXPRESS-FILEUPLOAD BEING USED HERE
};

Routes file:

router.post('/photo', function(req, res, next) {
    console.log("INSIDE OF THE ROUTE =======>>>>>");
    const userId = req.body.userId;
    const busketName = 'my-bucket-name';
    let newPhotosArray = [];
    var busboy = new Busboy({ headers: req.headers });
    req.pipe(busboy);

    busboy.on('finish', function() {
        const filesObj = req.files;
        console.log('FILES OBJ: ', filesObj);  // THIS IS LOGGED OUT AS NULL ON HEROKU - LOCALLY IT IS AN OBJECT WITH FILES

        // rest of code....
    });
});

The code works great when I use it locally. However, when I push the code to Heroku, req.files is null. Why is this?