Major Description
Policy updates to different policies within a service, when successful, update the service's policy version. If the update transactions are concurrent, and executed on different ranger-admin servers (in HA configuration), then it is possible that policy-version of the transaction that commits later overwrites policy-version of earlier transaction, effectively losing track of the first change.
If policy-version is updated after update to policy is committed, then the window of such loss is greatly reduced.
Similar considerations apply for tag updates.