It's not working - otherwise, I wouldn't have spent the time to come up with a workaround. However there's also now a possible confounding hardware problem. We have all 4 internal SATA drive bays populated and use 1 disk for system and 3 for data. Launchd has not been able to monitor watchpaths on two of the data disks (i didn't test the third) for a couple of months, but recently one of those two data disks has started experiencing timeouts. It seems possible that the failing drive could be affecting the neighboring drive's bus/controller/??? So maybe it's only a hardware problem and not a launchd problem at all. I'm going to wait until the disk is replaced before doing anything more with launchd.
Marit,
Launchd supposedly rechecks path monitoring checks every time the mount table is updated. Unfortunately, we don't log the transition from "it wasn't working" to "it now is being monitored" state. Is this genuinely not working for you? Or is the log message just concerning you?
davez