Since we migrated to ZENworks 11.1a (from ZENworks 10.3.3), a sizable fraction of our workstations no longer appear to be performing "full refresh"es properly. Specifically, the "Last Full Refresh" date on the workstation object in the ZENworks Control Center does not update, ever.

If I delete the workstation object from the ZENworks Control Center, and then refresh the workstation, the object gets re-created - but the "Last Full Refresh" date is blank, and it remains that way indefinitely (or at least over the course of months).

I can't say with certainty that there is data which isn't making it across properly from these workstations, but there are a number of suspicious behaviors which could be explained by a failure of proper communication; unfortunately, I don't have good records of most of them, and none of them seem to be completely consistent.

Many workstations began exhibiting this behavior immediately after the Agent upgrade. Others seem to have begun it since then, at possibly random times. (Some workstations began exhibiting a similar but worse behavior - in which not even the "Last Contact" date gets updated - immediately upon the server upgrade, but I'm not positive that that's the same problem.)

I've tried scanning through logs on a few affected workstations already, but they aren't the most penetrable of documents, and none of what I do understand from them looks particularly out of what appears to be the ordinary.

Any idea what could be going on here, or what sort of information to look for in the logs?