PDFKit is vertically flipping PDFPage initialised with image

Not sure if this is a bug as PDFKit is in Beta on iOS, but when I create a PDFDocument based on an array of images (using PDFPage(image:), it flips the image vertically.

@IBAction func export(_ sender: Any){
    let apdf = PDFDocument()
    var i = 0
    while i < arrayOfImages.count{
        let image = arrayOfImages[i]
        let pdfpage = PDFPage(image: image)
        apdf.insert(pdfpage!, at: i)
        i = i + 1
    }
    //Code for sharing the PDF Document
    let objectsToShare = [apdf.dataRepresentation()]
    let activityVC = UIActivityViewController(activityItems: objectsToShare, applicationActivities: nil)

    activityVC.popoverPresentationController?.sourceView = view
    self.present(activityVC, animated: true, completion: nil)
}

The output is this:

When it should be this:

I am 100% sure that the source images are not flipped because they are used elsewhere in the app. You can set the rotation of a PDFPage but I can't see any way to manually flip it back.