Correct I’m assuming this discussion is about the SmartApp software based autoLock
The hardware based autolock is controlled by this device handler where as the software based autolock is used in combination with the door open/close sensor by the above SmartApp. The reliability of the autolock feature depends heavily on the quality of the Z-Wave mesh and location of the lock. It also depends upon how the lock processes the commands, some locks don’t accept too many command too quickly. Hence the safest option is to use the delayed locking mechanism provided in the SmartApp which waits for a seconds to autolock the door (it also checks the door status before locking). This is also preferable practically since if you suddenly reopened the door, even with an immediate relock option it can take a second or so to lock it and in a immediate reopen scenario it could extend the deadbolt while the door was reopened. Delayed relocking the most reliable option.
Other things to look at to improve reliability
- Reboot the ST hub (using the IDE reboot command)
- Repair the Z-Wave mesh (using the IDE Repair command)
- Add a few active Z-Wave device (repeaters) around the house/between the lock and hub.