Thank you Jon for your help and patience, we are making progress!! As per your suggestion to verify the Error Log in HANA Admin Console, we re-generated the incident and then found a message specific to a short dump (Transaction ST22). As "luck" would have it, exactly the 2 affected users appear, and no others.
After some research of the dump, we found an OSS note for SP7 which seems relevant:
http://service.sap.com/sap/support/notes/2055414 (The project explorer does not display queries based on FBPAs). Since we are also using/transporting Open ODS functionality in our design, we strongly suspect that this is the cause of the error.
We are going to ask our Basis team to implement the Note, and hopefully it will resolve the issue. I will follow up once completed to provide status/feedback.
Not an easy issue to troubleshoot, but a big learning experience in how to troubleshoot any issue. Thank you again.