Checksum deployment may not occur if the files you have replicated are smaller than 10 kilobytes. By default, only files that are bigger than 10KB are deployed with a checksum deploy.
This default size can be configured for replication in the $ARTIFACTORY_HOME/etc/artifactory.system.properties file with the following flag (requires a restart):
Any files that are smaller than the value that has been set as above (XYZ) will not be deployed with checksum deploy. Instead, it will deployed as it is in a regular deployment.