I have setup IPN URL under notifications on my Sandbox account. When I do test payment and nothing found under IPN history. its seems Sandbox PayPal is not sending IPN’s to listener. When i did test using IPN Simulator and it works fine.
Any ides why it's not working
Whats an example of a PayPal Transaction ID created in the sandbox, for which you expect to receive an IPN? Are you sure you configured IPN for the correct sandbox business account in www.sandbox.paypal.com? Depending on your integration method, if it is not the current v2/orders you can specify a notify_url at transaction time to override the account-level IPN setting.
But really you should just do a Set up standard payments integration that calls your server for the v2/checkout/orders API and not need IPN at all. No reason to use that old asynchronous and clunky service.