After enabling some of the Agent policies (like Inventory Agent plugin Upgrade), the first replication to the Child NS works just fine. All settings selected for those policies are present on the Child NS. However, any other change done over the Schedule section or Targets (under the 'Apply To' section) like changing the frequency of the schedule or adding/removing targets, those changes are not replicated for some reason.
Check if the Policy has the Hierarchy Editable Properties (HEPs) enable for 'Resource Target' and 'Client Schedule XML' options (click on the Policy>right-click>Hierarchy>Properties). If so, uncheck them. The subsequent Replications will not overwrite what the Child Server has if those options are enabled. It is part of the design where the Child NS has enabled the ability to edit the Policy on the Child NS itself rather than using what the Parent NS has for that Policy. In most cases those options are not selected by Solutions have the ability to have them check if that is part of their default behavior.
For more information on this topic, please refer to HOWTO42297 "How Hierarchy Editable Properties (HEPs) works within an Hierarchy?"