Please check the content-metadata in the SAM for the related BOs. Generally we will miss that part.
Try with an Admin user and see whether it works , if it works it is an issue related to SAM.
I've already tried with 'Admin' user and confirmed that it is a SAM related issue.
I also have create/update/delete/execute on all content metadata, but that doesn't seem to resolve the error.
Please check under Secure Resources if you have any private objects which belong to the above BO's?
Kaushal, there was a known bug on 10.2HF2 that “Admin” user wouldn’t be able to create Hierarchy relationship unless assigned with a SAM role.
But a non-admin user having issue in your case looks similar to below C360 jira TCR-1898. Try the workaround mentioned in the link.
I wasn't able to open the link that you'd referenced; However, I was able to resolve the issue by trial & error.
Since this relationship BE has an HM enabled relationship entity bound to it, the following SAM settings must be enabled:
1. Provide CrUD/Execute on HM Profile
2. Provide CrUD/Execute on relevant Hierarchies
3. Provide CrUD/Execute on each individual relationship type
I already had item #2 and #3 above covered earlier. However, was missing #1 above.
The issue seems to have been resolved with the above SAM settings.