Why can't others see the message sent by Qq?

1. It may be that the mobile phone account has set permissions. You can check it in the settings, and you are advised to confirm it yourself. Sometimes you don't set permissions automatically.

2. If there is no authority, it may be that the account is advertised or other information is blocked by space. Similar to the state of space ban, I suggest you find QQ customer service.

Network problem, but since you said other people's numbers can be sent, that may be the second possibility. Suggest contacting customer service.