I'm using Enterprise Vault 8 SP3. I have a very similar issue to this one.
https://www-secure.symantec.com/connect/forums/user-able-see-all-vaults-has-no-permissions
I am able to clear permissions off the Vaults using EVPM and ZAP. This clears all permissions and everything looks good. Once the syncronize task runs again though, permissions are back to the incorrect way ( some users can view ALOT of vaults). The Vaults that are visible show only their own permissions on the permissions property tab and in the PermissionsBrowser. I've also disabled Inheritance and Permision sync in all my Mailbox archiving policies...but they are still being synced somehow ( and the Exchange Mailboxes themselves operate correctly. I.E. User A can see User B's Vault , but User A cannot see User B's Exchange Mailbox.
Any help?