req.file is always undefined no matter what I do

Question

I'm trying to upload a file to AWS S3 with multer using upload.single('image') but no matter what I do, req.file always returns undefined. I'm using postman to submit the form. I've tried the exact same code in a new project and it works. But when I try it in my main project, it won't work.

const upload = multer({
  storage: multerS3({
    s3: s3,
    bucket: "bucketName",
    acl: "public-read",
    metadata: function (req: Request, file: any, cb: any) {
      cb(null, { fieldName: file.fieldname });
    },
    key: function (req: Request, file: any, cb: any) {
      cb(null, Date.now().toString());
    },
  }),
});

router.post(
  "/upload",
  upload.single("image"),
  (req: Request, res: Response) => {
    console.log(req.file);
    console.log(req.files);
    return res.json({ status: "OK" });
  }
);