WeChat test number in the "WeChat Public Platform Interface debugging Tool" test interface successful but unable to passively reply to the user message why is it possible?

The test number for the development has been applied and has been successfully configured and verified on the Management test number page.
When you want to test the "passive reply to User message" interface, the message can be returned correctly in the Public Platform interface debugging tool, such as:

The developer documentation also says:

In the event of the following, the user will be issued a system in the public session, "the public number is temporarily unable to provide services, please try again later":
1, the developer did not reply to any content within 5 seconds
2, the developer replied to the abnormal data, such as JSON data, etc.

However, the user who has been concerned about the test number sends a message to the test number without receiving any messages, including "The public number is temporarily unavailable for service, please try again later", as mentioned in the document.
May I ask what this might be for?

Reply content:

The test number for the development has been applied and has been successfully configured and verified on the Management test number page.
When you want to test the "passive reply to User message" interface, the message can be returned correctly in the Public Platform interface debugging tool, such as:

The developer documentation also says:

In the event of the following, the user will be issued a system in the public session, "the public number is temporarily unable to provide services, please try again later":
1, the developer did not reply to any content within 5 seconds
2, the developer replied to the abnormal data, such as JSON data, etc.

However, the user who has been concerned about the test number sends a message to the test number without receiving any messages, including "The public number is temporarily unavailable for service, please try again later", as mentioned in the document.
May I ask what this might be for?

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