I had also checked that table but everything is fine.
The issue is not that Retro isn't triggering, its triggering.
The issue is some of the wagetypes in IT0014 which are changed from a past date aren't getting recalculated and arrears getting processed.
I checked both ways -
- increasing the amount against deduction wagetype already deducted in last period - in this case system should have brought fwd the difference amount to be deducted into /551
- reducing the amount against deduction wagetype already deducted in last period - in this case system should have refunded the difference amount to be paid into /551