Sorry for the delay in my follow-up. It turns out it was mainly a "me" problem.
During my initial configuration phase, I configured a GPO for the autoenrollment of client certificates but for testing purposes I limited the deployment of my new sccm gpo to a single test OU. By the time I enabled the automatic client push, I had forgotten about that.
Don't I feel stupid
Linked my sccm gpo to the appropriate OUs and eventually the client computers obtained a certificate and sometime after sccm succeeded in pushing out the client. As users came back from the weekend, the number of deploy sccm clients has been increasing.
Microsoft states: "If the site server cannot contact the client computer or start the setup process, it automatically repeats the installation attempt every hour for up to 7 days until it succeeds." so FN-GM was right about the possible need to delete old discovered that doesn't have a client yet, SCCM may have already given up on trying to install the client.
On a side note, I noticed that no XP machines showed up in sccm. Turned out to be that our XP systems were not getting the autoenrollment certificate. Did some research and found out that it's a known issue when using a Windows Server 2012 issuing ca. Disabling the IF_ENFORCEENCRYPTICERTREQUEST interface flag resolves the issue.
To disable the IF_ENFORCEENCRYPTICERTREQUEST interface flag use the following command on the issuing ca:
certutil -setreg CA\InterfaceFlags -IF_ENFORCEENCRYPTICERTREQUEST
Source:
Windows Server 2012 CA will not allow Windows XP to autoenroll
To answer my own questions:
1) Any idea what my problem might be?
automatic client push couldn't push the sccm client because our sccm solution was configured to use ssl and the clients where not getting their certificate. By the time I was checking, sccm had already given up pushing the client. Deleting 1700 devices in sccm that didn't have the client and letting sccm rediscover them and attempt to push the client resulted in lots of log entries which was useful. Some clients had no trace information on the install attempts (turns out to be a rare thing) while others had relevant information in their ccmsetup.log file
2) Any idea exactly which sccm log files would contain information about the automatic client push?
Check the ccm.log file on the server as the SMS_CLIENT_CONFIG_MANAGER component is the one that handles the client push. Also, as free780 stated, check the ccmsetup.log file on the client computer, you will sometimes find more relevant information there than on the server logs. If you don't see the ccmsetup setup and log file, check several other client system. The odd thing is that the server pushes the client installer via the admin$ share BEFORE there's a needs for the certificate to be in place on the client computer. So I'm not sure why on a few clients I wasn't seeing anything.
3) When a device is discovered, is the client automatic client push installation immediate? or is it schedule to happen later?
The push is immediately attempted but that doesn't mean you'll see it immediately.
Thanks for the help.