I'd hazard a guess that he's referring to:
Data Dictionary Reports -> DatabaseAdministration -> Locks -> Blocking Locks by User
If so, he's absolutely correct... it's using the V$ views exclusively, and therefore has an incomplete view of locking in a RAC database. That's also true of the Locks by User report in the same group, by the way.
4.0 is in Early Adopter mode, i.e. BETA.
We've had three 4.0 releases, EA1, EA2, and EA3.
EA3 came out on Friday and is available for download from the main OTN product page. Has more than 600 or so bug fixes from when EA1 was released back in July.
Is there a way to enable? Yes. Copy the report down to your user defined reports. Edit the query to go against GV$. This is what we have done for all of those reports for version 4 - it's just not in the release available for download, yet.