Jobs usually get hang when there is a connectivity or RSCD issue. Troubleshoot on the RSCD and its permissions and that should resolve the issue.
For point 2, We have checked RSCD agent connectivity/Permission with agentinfo command and it is getting successful.
what parts are in the snapshot job or component template ?
can you attach the job run log and the rscd from one of the hanging targets ?
this looks more like an agent connectivity issue and nothing more, since the same job is already successfully executed against couple of servers.
You may find this helful. PFA...
Another possibility could be a stale NFS mount on the target server.
if your snapshot or component template has the FileSystem Part it will perform a df -k, if you have a stale NFS mount this command will hang.
I have seen this occur several times.
I have found on some of the servers NFS mount was not responding.