Kaspersky Who Calls may have the following issues (and solutions) on Samsung devices:
Kaspersky Who Calls might not restart after the device is restarted. To fix this, allow autorestart for Kaspersky Who Calls. For example, use the Smart Manager app: go to Smart Manager > Memory > Autostart apps and set the Who Calls switch to ON.
Some steps may be different depending on the device model and version of the operating system.