To resolve the issue, please perform the following.
If only one agent is affected, click on the agent name, then on More dropdown on the right pane and select Retention Policy. Verify if agent is using Core default or custom retention policy. This need to be done on both Cores.
If all agents are affected, then make sure that Retention Policy matches on both Core. It's located in Core console, More (...) on the iconbar in top-left corner, Retention Policy
Please note that already built RP chain on the target Core will not be rebuilt after matching retention policies. Recovery Points are dependent on each other and this dependency is built during the replication process. The only way to force number of RPs to match is to delete the data on the target Core and re-replicate affected agents.