Hi,
The fact that this is only happening for older documents, the following analysis reports (contained within the notes) may be useful:
949162 - Follow-on documents exist, status I1111 and I1113 active
755769 - Status I1113, no item or header relations->analysis report
Depending on the SC header status in BBP_PD, then you'll know what report to use.
I hope this helps,
Kind Regards,
Lisa