Verify that your AppAssure build is not below 5.4.2.x. If it is, upgrade to the latest AppAssure release with update patch by navigating to our Download New Releases
On the source machine, verify in the Core Console events that the troubled machine not failing backups. If it is failing backups, search the error message in our Knowledge Base for a possible solution. Once resolved, monitor the backup jobs and the immediate virtual export. Perform a defragmentation of the Agent's volumes. If issues persist, open a service request with AppAssure support.