WebWatcher for iOS will record WhatsApp messages with a valid Unlimited Updates Package assigned to the selected iPhone. If you are still not receiving WhatsApp messages after assigning the Unlimited Updates Package, please take a look at the below screenshots to troubleshoot this issue.
Within the WhatsApp App itself under Settings > Chat Settings > Auto Backup, toggle Auto Backup to Daily.
The requirements for this feature are listed in the below screenshot. Please make sure the necessary changes are made to the iCloud settings if need be.