lag on Scheduled report

Hi All,

Good Day..

We are using Sep 12.1 RU1 MP1 on a windows Architecture,

We having scheduled reports configured and which is intended to run after 8 AM of every day. Initially it runs on proper time, after three months we noticed that the time is getting postponed and yesterday we notice that it ran on 11.30.

Can anyone suggest why this lag on Scheduled report?

Regards

Ajin