Correct! Even if the data is loaded at the beginning of the shift, it is old a hour later. However most if not all police agencies have written procedures that addresses this possibility.
Procedure and law states that a "hit" is not probable cause for an arrest. If the hit happens on a plate scanner the officer will then run the plate/person on his computer or through dispatch, to check that the want is still active.(See how this circles back to the original posters question). If it is for a wanted person, dispatch then calls the originating agency to see if the current want or warrant is still valid, if extradition is positive for out of state before an arrest is made. If it is still valid, a copy of the verification printout or warrant is attached to and part of the arrest record.
That is all for the officers and agencies protection from liability.
Courts sometimes screw up and do not cancel or vacate an active want. As long as the officer does CYA that liability attaches to the court not the officer.