Connect to Playback database in SQL Server management Studio (SSMS) and run the following queries (edit the date to reflect the earliest date based on playback's number of days set):
DELETE FROM spotlight_playback_alarms WHERE pb_timestamp < 'YYYY-MM-DD'
DELETE FROM spotlight_playback_states WHERE pb_timestamp < 'YYYY-MM-DD'
This will (obviously) purge old data that remains in the Playback database and should prevent the false reporting of alarms states in Playback mode. Stop the service (Spotlight Diagnostic Service) as it might keep writing to the Playback during that time - just for the time when running the above statements and then start it up again.