Retro not picking up People Group correction on Assignment

Summary:

We select the relevant sickness plan for each employee in the People Group on their Assignment record. We have found that when an employee's People Group is corrected to a different sickness plan the sick pay re-calculation is not getting picked up on the retro process.

Is this expected behaviour or something we need to amend in our configuration?

Content (required):

Version (include the version you are using, if applicable):

22D (HCM/UK Payroll)

Code Snippet (add any code snippets that support your topic, if applicable):