Scheduler pre-expiration event log

Hi,

I have a F800c running FortiOS 5.2.4 and I would like to use the "pre-expiration event log" feature available while configuring a one-time scheduler.

I tried several times to configure it but I never saw any log about policy expiration.

The strange thing is that I can configure it with the GUI but I never see any related command in the CLI...

Does anyone already used this feature?