Why can't China UnionPay Express always receive the verification code?

In the mobile phone system, the access of China UnionPay Express to read information is limited. The setting method is as follows:

1. First, open the settings on the phone desktop.

2. After opening the settings page, click Security to enter the security settings.

3. After entering the security settings page, click the application permission indicated by the arrow.

4. Next, click the application software China UnionPay Express.

5. In the following pages, you can allow China UnionPay Express to read short messages.