iOS Firebase appears to hang due to StoreKit (which isn't being used)

In the past few weeks something apparently has changed with xcode/Apple which is causing our iOS regression tests to hang on authentication using Firebase.

Googling the interleaved log error Error enumerating all transactions: Error Domain=ASDErrorDomain Code=509 "No active account" UserInfo={NSLocalizedDescription=No active account} seems to be related to "Store Kit".

The authentication method works perfectly fine when running the app - this only occurs in our regression tests.

Error enumerating unfinished transactions: Error Domain=ASDErrorDomain Code=509 "No active account" UserInfo={NSLocalizedDescription=No active account}
[OlyPro.AuthController][logout()]
Error enumerating all transactions: Error Domain=ASDErrorDomain Code=509 "No active account" UserInfo={NSLocalizedDescription=No active account}
[OlyPro.AuthController][email_login(vc:email:password:)]
$$$ + waiting for login to complete + $$$
$$$ + waiting for login to complete + $$$

func email_login(vc: UIViewController?, email: String, password: String) {
    
    os_log("[%s][%s]", log: .default, type: .debug, String(describing: self), #function)
    
    Auth.auth().signIn(withEmail: email, password: password) {(authResult, error) in
        os_log("[%s][%s] signIn", log: .default, type: .debug, String(describing: self), #function)
        if let user = authResult?.user {
            NotificationCenter.default.post(name: .loginComplete, object: nil, userInfo: nil)
            os_log("[%s][%s] * signIn success %@ *", log: .default, type: .debug, String(describing: self), #function, user)
            if vc != nil {
                vc!.performSegue(withIdentifier: "email_login_segue", sender: self)
            }
        } else {
            NotificationCenter.default.post(name: .loginFailed, object: nil, userInfo: nil)
            os_log("[%s][%s] * signIn fail :: %@", log: .default, type: .error, String(describing: self), #function, String(describing: error))
            if vc != nil {
                let dialogMessage = UIAlertController(title: "Attention", message:  error?.localizedDescription, preferredStyle: .alert)
                let ok = UIAlertAction(title: "OK", style: .default, handler: { (action) -> Void in
                    os_log("[%s][%s] Ok button tapped", log: .default, type: .debug, String(describing: self), #function)
                })
                dialogMessage.addAction(ok)
                vc!.present(dialogMessage, animated: true, completion: nil)
            }
        }
    }