Disabled Check Constraint
Check constraints are often disabled when bulk loading data into a table to improve performance. It's easy to forget to re-enable them after the event, meaning the check constraint is no longer applied.
Re-enable the constraint, if still needed. Note that re-enabling the constraint will cause all rows to be checked against the constraint, so this should be considered when scheduling the SQL.
Drop the constraint if no longer needed.
Any suggestion from Aireforge should be thoroughly tested before being implemented into production.