In this section of the API documentation https://docs.opsmanager.mongodb.com/current/tutorial/automate-backup-restoration-with-api/#add-the-restore-link-to-the-automation-configuration there is a line that reads:

In the processes array, add the backupRestoreUrl field to each mongod to be restored. Enter the restore link as the field’s value.

Since the arbiter does not really contain cluster data, we assumed this instruction was correct and that the link only needs to be specified for the mongod stanzas. However, Ops Manager automation does not like this since it runs some basic checks to make sure the link is present for all members in the array. As such, lets update this piece to mention both mongod or arbiter elements and void issues. In our testing, once it was added to the arbiters, the restore completed successfully.

I suspect this will also apply to the cloud manager docs for the same process.

Thanks!