macos - Unable to keep remote job running on OS X

I just got a MacPro and am trying to work remotely on it. But when I ssh into it and start a job, put it in the background, and log out, the job apparently goes to sleep. So when I log back in and check how long it has been running, it appears to have simply gone to sleep for the period I'm logged out, and then restarts when I log back in. Tried nohup/disown and a bunch of other fixes proposed for related situations, but these do not seem to work. I also tried "| at" to see if I could start the job at a fixed time, but when I logout and come back later, I find this is not working either.