When Troublshooting this feature it is important to note the roll of the dbo.alprRefLookup table
It's the table that gets written to when you Search and Update a plate.
It houses the incorrect read as well as a reference to what the corrected plate is.
So when doing subsequent readings the plate the system checks this table to see if there is a corrected version and then diaplays the corrected version on the HH.
Be sure to check this table if there are any issues with the functionality and make certain the records apper correctly in the table.