Whenever you have changed the classification setup, you need to regenerate the counters
You can do this manually, from SOAdmin - System Options - Status Monitors
Or automatically from Travel Gateway
Note, if you have a large database it may take a while to regenerate.
Real-time updating will update the counters "as things happen", but it will slow the system down a bit depending on how many records you have in your database. If you are experiencing performance issues, turn off "Update all counters in real-time".
What does the period duration mean?
The period is a sliding window, so you should regenerate every night, otherwise the ”in period” counters are not exactly valid. If you have set the period to 30 days, for example, the period will always be 30 days from the last time the counters were regenerated. You should therefore regenerate the counters frequently (preferably each night), so that the counters are as up-to-date as possible.