Adding above I also found the process
1. Create a PR, transfer to SRM;
1.5. Check in BBP_PD on the item level field SOURCE_REL_IND. It should be X
1.6. Create PO from sourcking cockpit. Order the PO and make sure it's Ordered, not Error in Process. Validate in ECC as well.
2. Check in BBP_PD on the item level field SOURCE_REL_IND. It should be blank
3. Wait for a while, say 1 - 2 minutes. WF-BATCH could be locking the PR
4. Change the same PR in ECC, with non quantity fields, such as delivery date
5. Transfer PR to SRM (BBP_EXTREQ_TRANSFER)
6. Check in BBP_PD on the item level field SOURCE_REL_IND. It should be still blank - no sourcing is possible for this item
Now going through step 1.5 -> my Source_rel_ind is not showing X.
Regards
Gaurav Gautam