Inconsistancy in alerts notifications through Webhooks

I am currently on Developer Plan. I have an alert rule configured to Send Notification through Webhook .
Webhook integration was successful. Webhook endpoint is receiving notifications.
However, I observer inconsistency w.r.t notifications. Webhook endpoint isn’t receiving all the Issue notifications it is supposed to. Basically it works sometimes but not all the time.

Is this because i am currently in Developer Plan (it says limited alerts in plan details). Or am i missing something here.