To protect the backup using snapmirror, you need to have a volume in secondary to protect the backup. In SMO, the snapshot will transfered to secondary volume after backup. you are not required to create another volume (i hope you mention volume as volume group, if not correct me) in secondary for clone. The clone can be created from snapshot from the secondary volume with thin provisioning and later testing you can split the clone volume to separate volume using split functionality.
Normally it will restore from primary. If the snapshot not available in primary then it will take it from secondary.
I don't see any log attached for the failed clone operation.
Please open a case with support team.
Also please note that in SMO 3.2 if you try to clone from secondary backup, SnapManager checks whether the primary backup still exists. If the primary backup is not freed and still exists, then the backup on the primary is accessed, and not the backup on the secondary. This could end up in an operation failure if remote host has no connectivity to primary filer. In case of no connectivity to primary storage, you should consider freeing your primary backup so that secondary backup is used for the operation.