Workflows not displayed in SO01 for IDOC error

Hi Experts,

I have searched the whole forum for 2 days now and still could not find an answer to my question.

Issue:

IDOC (message type:ORDERS) with error 51 has stopped triggering workflow and creating items in SO01 for the users.

This used to work a couple of months back but stopped working recently.

Findings till now:

The start event INPUTERROROCCURED is not active in the process code.

This was not active even earlier I believe. Checked the tcode OY18 for the changes on the table SWETYPEENA.

But no changes were made, in fact the event was never active in production.

Please let me know if it is possible to trigger workflow without event being active.

Also provide how to check for any other changes.

Thanks

Ram