Please see info below regarding arrears not generating for an employee:

Case: 66266183
I have reviewed the EE record for 1054399 and there are multiple salary changes to the EE's record in the period 202442. As previously advised, the system does not handle arrears calculations in these scenarios and manual timesheets need to be input.
However, as in this case, the system does generate a salary (issues only with arrears).
So yes, to confirm, the issue affects arrears calculations only and salary generation should not be affected by multiple Salary lines being input in same period.