We discovered some timesheets that had not been posted to WIP. This was because our "Post to WIP" job was sending in a "start date" parameter to the PAC_PRC_POSTTOWIPS_SP that was after the timesheet transaction date.
I have seen that other users have created portlets to detect "posted" timesheets that have not been posted to WIP. What tables/columns are you using to detect these timesheets?
Note this is not an issue of records stuck in the Invalid transactions table. They don't make it that far.