IPN issues with Paypal Standard

I am using Paypal Standard gateway. I have followed the instructions regarding troubleshooting IPN issues as well as the one specific to Paypal Standard but still have problems with give not getting IPNs.

Here is what I tried:

1. I tested with the IPN simulator on paypal developer and see the message that “IPN was sent and handshake was verified”
2. Then I saw that the IPN setting on the paypal account was not set at all although it was enabled on the give setting. I enabled it with the “https://afutureforeverychild.org/?give-listener=IPN” as suggested.

Now I see the IPN history on paypal and it shows that IPN was delivered successfully with return code 200

3. I tried resending the IPNs – seems to go through but the donations stills stay in pending state
4. I also tried turning off the IPN setting in give plugin as suggested to see if that would work but no success.

Any suggestions as to what I should try next?

Thanks for your help.
Madan