Kaspersky Who Calls has the following known issues:
If you turn on automatic call blocking, all incoming calls identified as spam by the app are blocked without an incoming call notification and won't appear in your call log.
If you add a number to your local spam list, updated information about this number won't appear in your call log.
If the app doesn't get information about the number during an incoming call, updated information about this number won't appear later in your call log.