Below is the issue we have faced after upgrading the SRM to 8.3.1
IP customization is falling on RHEL 5 and 6 VM with SRM 8.3.1
IP customization previous worked on these RHEL versions with SRM 6.5
IP customization work with RHEL 7 VMs which can utilize the SAML tokens for authentication.
It looks like changes that happened between SRM 6.5 and later versions, that caused the conflict with LDAP on your RHEL6 machines. Prior to the changes, SRM performs script transfer using the VIX protocol that has little to no authentication. This master access method worked from vCenter, where SRM would transfer the script through vCenter, and then directly to the ESXi host and eventually the VM, without any authentication or tokens involved.
For security reasons, this is obviously a weakness. This has changed and is now enforced, that instead, we use a SAML token authentication, through an SSO Solution User, that is created when SRM registers with the PSC/SSO and vCenter. This new method also meant we needed to upgrade how Tools operates and allow it to be able to be apart of that process with SSO, thus the vgAuth part of the tools.
This process now impersonates the root account to execute scripts inside the GuestOS that are directly tied to an authentication token through SSO.
Also as you see above, SRM only contacts SSO to get authentication, but outside of that, SRM itself transfers the script now to the ESXi host and then the VM, instead of vCenter doing it. This new process forces us to authenticate and use the benefits of the temporary SAML token for activities like this. This is also the exact same process if you run custom scripts inside the Guest OS on your plans.
We have seen cases where LDAP and now with you, openLDAP, cause a conflict with our ability to impersonate on the Guest OS. Unfortunately, like any other third party application or solution that conflicts with our operation needs to be addressed from the offending application itself. In this case, it appears SSSD works as proven by your tests.