We observed that even the Paystub with small or big number of employees, when processed the status is reflected as "Submitted". Which is not processing further and seems to be stuck there.
There is a web service that is processing the records and then updating the total in HEAT. The Web Service was failing and not sending back an update to HEAT and hence HEAT was remaining in the limbo.
The issue was with the running total for Net Pay currency field. It was designed to only accommodate Currency (10,2). We changed it to support Currency (14,2).