TN EDI Delivery Tasks going into PENDING status


We have migrated from wM 9.5 to 9.12.
We are facing issues for deliveries using “EDIINT SimpleDelivery”.
We could see that the http thread call (pub.client.http) running for a long time and its not getting timed out or getting terminated. The task status remains in “PENDING” and is not delivered to partner.
If we reprocess the transaction, it gets delivered with a new task and still the old task stays in PENDING. is set to 600 but it is not honored for this case.

Did anyone face similar issue and able to fix this? Any advice is appreciated.

Thanks in advance,