CoreML: "Failed to evaluate model 0 in pipeline" with image classifier

I'm trying to classify an image with a custom model as shown below. The input image is of correct resolution (299 by 299). However, when calling prediction(image:) I get an error "Failed to evaluate model 0 in pipeline"

// Image is given
let pixelBuffer = pixelBuffer(from: image)

if let pictureClassifier = try? PictureClassifier() {
    var prediction: PictureClassifierOutput?
    do {
        prediction = try pictureClassifier?.prediction(image: pixelBuffer)
    } catch {
        if let mlModelError = error as? MLModelError {
            print(mlModelError.errorCode, mlModelError.localizedDescription)
        }
    }
}