It guarantees that all replications will report state in sync with each other on search, not that the last reported state is the actual current state of the index.
As the numerous comments here and the documentation states, the refresh flag on your insert/update will ensure that changed data in that request is consistent for queries after.
Where did you get the behavior you described? Are you sure you're not confusing this for the separate refresh command itself? That is not attached to any particular insert/update.