You need to go into your holiday scheme and update the average pay type to base rate only. To do this, follow these steps.
Click Settings, then click HR.
Click Employee, click Holiday Schemes.
Select the correct holiday scheme.
From the Average Pay Type dropdown, select Base Rate Only.
Click save.
You'll then need to check your pay rate sheet and ensure the base rate field contains an hourly rate. To do this, follow these steps.
Click Settings, then click Finance.
Click Payroll, then click Rate Sheets.
Select the relevant rate sheet.
Select the Revisions tab.
Select the most recent revision.
Select the Details tab
Enter the value in the Base Rate (Per Hrs) column.
Click save.