Chatbot message delayed or not received

Hello,
I was working on a chatbot. When I send message from my php backend it's showing the message sending successful but in my zoom application I'm not receiving it (actually receiving it but not immediately). I've checked my phone it's receiving the message but in Mac app it's not receiving. I've tried with Postman it's instantly send the message to both android and Mac app. But when I tried with php backend the Mac app not receiving it. If i restart the zoom application the message does appear.
Can anyone tell me what might be the issue.
Note: I'm still using it in test mode.