To resolve this error, there are 2 things to do, both in Access EasyPay and ePortal:
EasyPay
Go to the Leave module, Process Leave.
Highlight the affected employee and click Delete.
In the Process Leave, click Initialise.
Select the Leave Policy that contains the leave type and click Next.
Bring this employee over.
ePortal
Log in as admin.
Click Settings, eleave Settings, Configuration.
Click Copy all leave types from EPE.