I've had a rule I made when I first purchased my Hubitat. It stopped working a week ago. No changes on my part. I've updated to the latest Hubitat software on my C8.
The rule:
When Front Door Lock unlocked ...
Wait 5 minutes
Lock Front Door Lock
Seems simple enough, and it was working just fine until a week ago or so. I have another rule that polls the lock every 15 mins to update its status.
Without more information, it's hard to say more -- other than the fact that the Basic Rule you shared seems like it should do (and used to do) what you expect.
What specific version? Check Settings > Hub Details to see for sure. If you are not on at least 2.3.9.147, you may be running into a bug from older versions of 2.3.9.
If that doesn't help, see this document for things that would be helpful to know or share:
Specifically, see the parts about enabling app logging and looking at device event history (as one total guess: maybe your lock isn't reporting "unlocked" status to the hub, so the rule never triggers--but this kind of troubleshooting will save you from needing to guess).
I'm running into the same issue as the original poster. My hub is running version 2.3.9.154. I updated from version 2.3.8.xxx (honestly not sure which version of 2.3.8).
But every since I updated, my Kwikset Z-wave lock (device type "generic z-wave lock') stopped working completely. By that I mean it :
won't respond to apps
won't unlock/lock while in Device edit screen
won't unlock/lock while in a dashboard
won't provide battery status
in z-wave settings, last message was time of the hub firmware update
I do, however, still see it in the Z-wave device graph
The same information requested above may be helpful to share, but with the extra information you shared, it's seems unlikely you'd find much useful things there, as it sounds like the device has stopped communicating. This could be coincidental; for example, do you know that the batteries in the lock are good? (Don't trust the percent reports; Z-Wave and Zigbee are not known for helpful battery reporting, though it can be somewhat of a guide.)
I once had to "reboot" an old Schlage lock to get it to communicate wth the hub, which I attributed to a device oddity. Perhaps the same would be helpful for you if you have not tried this yet (removing the batteries for a few seconds then re-inserting).