Running element twice per year

In our company there's an element must run twice per year.

one in the first of the contract (ex. Jan) and the other in the mid of contract(ex. Jul).

There's an update done on some of employees in a third period(ex. Oct).

When I run the retroactive on these employees for this element, the formula doesn't run in this third period.

what's the reason.

The man who made the setup is an ex. employee.

Can anyone help me.