Idoc Status 30

Hi Expert ,

I believe that most of you already familiar with the issue which is idoc stuck on status 30.
However , I still cannot find any solution yet.

Here is my problem :

I have a scheduled job to process idoc status 30 daily. However , it didn't work since few days ago and there is no changes recently.
I did checked the job and there is no error and the job status is finished.

WE20 setting: Collect Idocs /  output mode 4.

My question is:
Any other settings or configuration that I can check ?

Thanks.