Virtual standby or virtual export are failing with this error "Failed to enqueue continuous export of 'server' to 'server-export' on target 'vcenter:443'. Reason: Sequence contains no elements".
Taking a look at the recovery points, it is noticed that the last recovery points are orphaned.
The cause of the orphaned recovery points needs to be fixed first.
In case of broken replications with only the target core recovery points being orphaned, the recovery points needs be deleted, then replication deleted and recreated to ensure the recovery points chain is fixed.