SwiftyDropBox Auth flow issue

Thanks for the quick reply, Greg.

SwiftyDropbox version: 4.3.0

iOS version: 11.2.2

'open URL' code (identical to reference code):

func application(_ app: UIApplication, open url: URL, options: [UIApplicationOpenURLOptionsKey : Any] = [:]) -> Bool {
    if let authResult = DropboxClientsManager.handleRedirectURL(url) {
        switch authResult {
        case .success:
            print("Success! User is logged into Dropbox.")
        case .cancel:
            print("Authorization flow was manually canceled by user!")
        case .error(_, let description):
            print("Error: \(description)")
        }
    }
    return true
}