When I go to look at my jobs in the disk section over some of the vms' in the backup copy jobs I see a red exclamation mark. I realise that this is not good, I rerun the backup copy jobs and these sometimes go away and then come back again later.
Yes I think you have hit the nail on the head. I think that my jobs because there are a bunch of them are not finishing in the time period. So as I understand it, if you set the copy every.. to 1 day for example and you backupcopy job has not yet finished at X hour the next day, then it fails.
Yes, during next job cycle backup copy job will transfer the data it was missing on the previous run. If your backup copy jobs cannot complete within the sync interval, then you can either extend the interval or re-configure your backup copy jobs to send less data (use jobs with less VMs added) to the repository.