The last couple days I have received an error email indicating that snapshot replication to AWS was skipped because a newer snapshot is available. I'm looking at the replication status and I see:

Id                        : 15008898
    Protection Domain         : Exchange
    Replication Operation     : Sending
    Start Time                : 04/09/2021 19:49:01 MDT
    Remote Site               : *RemoteSite*
    Snapshot Id               : 15008893
    Aborted                   : false
    Paused                    : false
    Bytes Completed           : 75.22 MiB (78,870,811 bytes)
    Complete Percent          : 3.2552084E-4

    Id                        : 14973755
    Protection Domain         : ERP
    Replication Operation     : Sending
    Start Time                : 04/08/2021 18:00:01 MDT
    Remote Site               : *remoteSite*
    Snapshot Id               : 14973750
    Aborted                   : false
    Paused                    : false
    Bytes Completed           : 1.4 GiB (1,508,006,895 bytes)
    Complete Percent          : 15.308814

    Id                        : 15016248
    Protection Domain         : Linux
    Replication Operation     : Sending
    Start Time                : 04/10/2021 01:05:01 MDT
    Remote Site               : *RemoteSite*
    Snapshot Id               : 15016238
    Aborted                   : false
    Paused                    : false
    Bytes Completed           : 0 bytes
    Complete Percent          : 0.0

The error email is referring to ERP protected domain, but it looks like none of the protected domains have replicated to AWS since April 8. They are scheduled to replicate every 2 days, except ERP which is scheduled to replicate daily.