Recalculation process producing different results to a payroll run or QP

Summary:

I have created a balance for our SHP calculation with a weekly frequency. This balance is populated using the flow, Adjust Multiple Balances, with the last 52 weeks of overtime payments relevant to SHP.

When I run a payroll to process an annual leave absence the payroll run looks at the SHP balance and calculates correctly over the 52 week retrospective period. However if I create a Retroevent in a previous period and run the recalculation process, it does not find any values in the balance for the previous 52 weeks, so no SHP payment is made.

This has worked in another pod but when adding to a new pod the recalculation process does not produce the expected results, only during a payroll run is the balance correctly used.