OE_ORDER_PUB.PROCESS_ORDER giving ATP Schedule error for Non ATO Items when called from package

We did POC on OE_ORDER_PUB.PROCESS_ORDER API and this worked absolutely fine for all Item types when we tested using Anonymous block. Order lines have got successfully rescheduled as well to expected date. However when we created package for the same and called it from Conc program, API is working only for ATO Item types and failing for all other Item types (Standard/PTO/KIT…) it is giving Error as below. For ATO Items it is working fine.

Process Order return_status is E
message is: Scheduling failed: ATP Processing error. Available Date: 13-FEB-20