The users are not displayed in the Kayako Desktop. This issue occurs when the database tables linked with visitors/users have reached their maximum size.
To fix this, you need to clear a couple of database tables using the following MySQL queries to clear them:
DELETE FROM swsessions; DELETE FROM swvisitorfootprints; DELETE FROM swvisitorpulls;
Note: Always take the database backup before making any changes to it.
The users are successfully displayed in the Kayako Desktop.