This issue can be caused by the following.
New salary exists with date effective the same or greater than the increment due date.
Increments are not maintained via CorePersonnel yet auto_increment on pay_group is N.
To resolve this, follow the steps below.
Click CorePersonnel, then click Maintenance.
Select Salary Administration, then select Maintain HR Salary Amendments.
Query the employee.
Select the required appointment.
On the Salary Details tab, at the bottom, note the effective date of the latest row.
At the top of the screen, click Salary Details, and note the increment due date.
If a salary exists as of or greater than the increment due date, the increment job will not create a new increment or roll onto the increment due date.
📌Note: Further information is available on increments and their rules.