Please be more specific about the diagnostic and the context of your question.  First, under Main Form, there is no #12 although there is Sch E > 12 = Sch E.

It sounds like you may have linked the attachment to Sch E but did not index it to any activity.  Suggest you take another look at your entries on the e-file Attachment page.

If that's not the issue, you'd need to come back with more details.

In case your issue is the same as what's discussed in the thread below...

https://proconnect.intuit.com/community/proconnect-tax-discussions/discussion/re-i-created-attached-...