In a Pay - Why doesn't the base hourly hours auto adjust to allow for leave entered in a timesheet?

Hi

I've started using timesheets to record leave taken. I have selected the option on the leave item to automatically adjust the base hourly hours. When I run a pay the base hours do not auto adjust down by the leave hours entered.

For example

* a normal pay is 76hrs 

* annual leave entered into timesheet is 8hours

Expectation is pay should adjust to:

Normal base hours 68hrs

annual leave 8hrs 

It is actually showing as: 

Normal base hours 76

annual leave 8hrs

Is there a fix for this?

If I don't use timesheets and enter the leave into the pay the hours auto adjust... 

Thanks for your help.