You receive a replication alert email with Missing "Replication Frequency" setting in it. You can see the same alert in the 'alerts' widget at the dashboard.
Missing "Replication Frequency" setting alert means that all the servers listed in this section of the email have the Check RPO health option enabled (it is always enabled by default when a new server is added) but the value has not been specified:
As a result, Acronis Recovery Console cannot monitor RPO.
On the Servers tab, locate the servers generating this alert, then open each server's page in your browser and update the setting. Make sure that you have selected the correct server instance as if a server is replicated to Acronis Cloud, it has 2 instances: one Local and one Remote.
You may either disable RPO check, if you don't need some servers to be monitored, or set an exact value like 1 hour for hourly backup, 24 hours for daily backups, or your own setting.