I have an inconsistent and intermittent issue with Patch Management DAU updates not being delivered to some - but not all - managed devices. Full error message is "Could not download bundle content for Discover Applicable Updates [Windows-x86-en-WIN7sp1] because a ZENworks Server could not be located." Two different DAU variants are involved, hence the [bracketed] piece. For each of the individual DAU variants involved, some associated devices work perfectly day in, day out, while a couple do not. Adding to the mystery - I've seen this issue in the past and it may disappear tomorrow through no action on my part, and then pop back up on the same or different devices some time in the future.

Any clues?