nib must contain exactly one top level object which must be a UITableViewHeaderFooterView instance

I am running into a weird issue when creating a customHeader for my tableView. the error that I am receiving is the following:

nib must contain exactly one top level object which must be a UITableViewHeaderFooterView instance

I ran through my code and xib file as well as examples but I couldnt find anything wrong any ideas I am missing?

The header Xib was created with a regular view and then a sub view with a label, the class was created with the following:

CustomTableHeader Class:

class CustomTableHeader: UITableViewHeaderFooterView {
    static var CustomTableHeaderIdentifier = "CustomTableHeader"
    @IBOutlet weak var titleLabel: UILabel!

    override awakeFromNib(){
         super.awakeFromNib()
         self.titleLabel.text = "Header"
    }

    override func prepareForReuse() {
        super.prepareForReuse()
    }
}

ViewController Class:

class ViewController: UIViewController, UITableViewDelegate, UITableViewDataSource {
    @IBOutlet weak var tableView: UITableView!

    override func viewDidLoad() {
        super.viewDidLoad()

        self.tableView.register(UINib.init(nibName: CustomTableHeader.CustomTableHeaderIdentifier, bundle: nil), forHeaderFooterViewReuseIdentifier: CustomTableHeader.CustomTableHeaderIdentifier)
    }


    //Other Methods
     func tableView(_ tableView: UITableView, viewForHeaderInSection section: Int) -> UIView? {
         if let header = tableView.dequeueReusableHeaderFooterView(withIdentifier: CustomTableHeader.CustomTableHeaderIdentifier) as? CustomTableHeader {
            header.titleLabel.text = "Section 1"
            return header
     }
}